Low Dust Additives Comprising Emulsified Powder For Joint Compounds And Joint Compounds Thereof

ABSTRACT

The present invention relates generally to wall repair compounds such as joint compounds, spackling compounds, and the like used to repair imperfections in walls or fill joints between adjacent wallboard panels. Particularly, the present invention relates to such a wall repair compound comprising a dust reduction additive that reduces the quantity of airborne dust generated when the hardened compound is sanded and also exhibits improved adhesive properties. The dust reduction additive also imparts adhesion to the wall repair compounds to which it is added, for example to a joint compound. The dust reduction additive is a powder prepared from colloidally-protected, wax-based microstructure dispersions.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims benefit of U.S. Provisional Application62/312,209, filed Mar. 23, 2016, the contents of which are incorporatedherein by reference.

TECHNICAL FIELD

The present invention relates generally to wall repair compounds such asjoint compounds, spackling compounds, and the like used to repairimperfections in walls or to fill joints between adjacent wallboardpanels. Particularly, the present invention relates to such a wallrepair compound comprising a dust reduction additive (DRA) that reducesthe quantity of airborne dust generated when the hardened compound issanded. The dust reduction additive also imparts adhesion to the wallrepair compounds to which it is added, for example to a joint compound.The dust reduction additive comprises a powder prepared fromcolloidally-protected, wax-based microstructure dispersions.

This invention also relates to a composition for a joint compound foruse in filling and coating the joints between adjacent panels of gypsumwallboard. More specifically, it relates to a composition for alightweight joint compound of the setting or drying type that generatesless airborne dust when the set or dried joint compound is sanded, andadditionally provides for more uniform gloss retention upon painting.

BACKGROUND

Interior walls of residential and commercial buildings are oftenconstructed using gypsum wallboard panels, often referred to simply as“wallboard” or “drywall.” The wallboard panels are attached to studsusing nails or other fasteners, and the joints between adjacentwallboard panels are filled using a specially formulated adhesivecomposition called joint compound to conceal the joints.

The procedure for concealing the joint between adjacent wallboards, andthereby producing a smooth seamless wall surface, typically includesapplying soft, wet, joint compound within the joint or seam formed bythe abutting edges of adjacent wallboard panels using a trowel or thelike. A fiberglass, cloth, or paper reinforcing tape material is thenembedded within the wet joint compound, and the compound is allowed toharden. After the joint compound has hardened, a second layer of jointcompound is applied over the joint and tape to completely fill the jointand provide a smooth surface. This layer is also allowed to harden. Uponhardening, the joint compound is sanded smooth to eliminate surfaceirregularities. Paint or a wall covering, such as wall paper, can thenbe applied over the joint compound so that the joint and the drywallcompound are imperceptible under the paint or wall covering. The samejoint compound can also be used to conceal defects caused by the nailsor screws used to affix the wallboard panels to the studs, or to repairother imperfections in the wallboard panels, so as to impart acontinuously smooth appearance to the wall surface.

Various drywall joint compounds are known for concealing joints betweenadjacent wallboard panels. Conventional joint compounds typicallyinclude a filler material and a binder. Conventional fillers are calciumcarbonate and calcium sulfate dihydrate (gypsum), which are used in“ready-mixed” joint compounds, and calcium sulfate hemihydrate(CaSO4-1/2H2O; also referred to as plaster-of-Paris or calcined gypsum),which is used in “setting-type” joint compounds. Ready-mixed jointcompounds, which are also referred to as pre-mixed or drying-type jointcompounds, are pre-mixed with water during manufacturing and requirelittle or no addition of water at the job site. Such joint compoundsharden when the water evaporates and the compound dries. Setting-typejoint compounds, on the other hand, harden upon being mixed with water,thereby causing dihydrate crystals to form and interlock. Setting-typejoint compounds are therefore typically supplied to the job site in theform of a dry powder to which the user then adds a sufficient amount ofwater to give the compound a suitable consistency.

The Koltisko, Jr. et al. U.S. Pat. No. 4,972,013 provides an example ofa ready-mixed (wet) joint compound including a filler, binder,thickener, non-leveling agent, and water. The McInnis U.S. Pat. No.5,277,712 provides an example of a setting (dry mix-type) joint compoundincluding a fine plaster material, such as stucco (a material whichimparts internal strength) and methyl cellulose (which providesworkability and water retention) to the joint compound. Additionalexamples of joint compounds are provided in the Brown U.S. Pat. No.4,294,622; the Mudd U.S. Pat. No. 4,370,167; the Williams U.S. Pat. No.4,454,267; the Struss et al. U.S. Pat. No. 4,686,253; the Attard et al.U.S. Pat. No. 5,336,318; and the U.S. Pat. No. 5,779,786.

A spackling compound is disclosed in the Deer et al. U.S. Pat. No.4,391,648. While joint compound and spackling compound do many of thesame things and are both smeared onto walls to hide flaws, spacklingcompound is generally lighter, dries more quickly, sands more easily,and is more expensive than joint compound. For simplicity, jointcompound, drywall joint compound, and like expressions are usedthroughout this specification to refer to wall repair compoundsgenerally, including joint compound and spackling compound.

Sanding hardened joint compound can be accomplished using conventionaltechniques including power sanders, abrasive screens, or manual sanderswhich consist simply of a supporting block and a piece of abrasive papermounted on the block. Sanding the joint compound, however, produces alarge quantity of an extremely fine powder which tends to becomesuspended in air for a long period of time. The airborne particlessettle on everything in the vicinity of the sanding site and usuallyrequire several cleanings before they can all be collected, therebymaking cleanup a time consuming and tedious process. The particles mayalso present a serious health hazard to the worker.

The airborne particles are highly pervasive and can enter the nose,lungs, eyes and even the pores of the skin. Results from a studyconducted by the National Institute for Occupational Safety and Healthfound that dust levels in 9 out of 10 test samples taken at test siteswhere workers were finishing drywall with joint compound were higherthan the limits set by OSHA. The report also said that the dust may notbe safe even when it falls within the recommended limits. In addition,the study found that several dust samples contained silica and kaolin,material founds in clay that have been found to cause permanent lungdamage. The report recommended the use of local exhaust ventilation, wetfinishing techniques, and personal protective equipment to reduce thehazard.

In an effort to reduce the dust generation and cleanup problemsassociated with the sanding of conventional joint compounds, variousattempts have been made to develop specialized dustless drywall sanders.The Matechuk U.S. Pat. No. 4,782,632, for example, discloses a drywallsander including a sanding head designed to minimize the release of dustand further discloses attaching a vacuum cleaner to the sanding head tocollect the dust. The Krumholz U.S. Pat. No. 4,955,748 discloses adustless drywall finisher which uses a wet sponge to prevent theformation of airborne dust.

Dust remains a problem, however, when conventional power sanders or handsanders are used to sand conventional joint compounds. A need thereforeexists for a joint compound that can be sanded using conventionalsanders without producing a large quantity of fine particles capable ofbecoming suspended in air. It would also be desirable to provide anadditive that could be mixed with commercially available joint compoundsto inhibit the formation of airborne particles during the sandingprocedure without otherwise interfering with the properties of the jointcompound.

A composition of the present invention addresses the above discussedproblems of dust generation. The emulsified powder of the presentinvention comprising colloidally-protected, wax-based microstructurescan be added to a wall repair compound, for example, a joint compound,to serve as a dust reduction additive. In addition, this emulsifiedpowder improves adhesion of the joint compound, and therefore, allowsfor a lowering of the binder to be used in the joint compound. Theinvention results in a joint compound with improved properties fordrywall finishing.

SUMMARY

The following presents a simplified summary of one or more aspects inorder to provide a basic understanding of such aspects. This summary isnot an extensive overview of all contemplated aspects, and is intendedto neither identify key or critical elements of all aspects nordelineate the scope of any or all aspects. Its sole purpose is topresent some concepts of one or more aspects in a simplified form as aprelude to the more detailed description that is presented later.

The present invention provides a wall repair compound, such as a jointcompound or spackling compound which, when sanded, generates a lowerlevel of airborne particles than conventional joint compounds. Inaddition, the joint compound of the present invention also has excellentadhesive properties, and water repellent properties.

More specifically, the present invention provides a wall repair compoundwhich includes a dust reduction additive. Generally, the wall repair orjoint compound includes a sufficient amount of the dust reductionadditive so that when the joint compound is tested as described in thisspecification, it generates a lower quantity of airborne dust than thejoint compound would produce if it did not contain the dust reductionadditive.

Disclosed herein are embodiments of a low-dust joint compound which cancomprise water, preservative, and dust reduction additive (“DRA”), whichcomprises a powder prepared from colloidally-protected wax-based(“CPWB”) microstructures.

Generally, the dust reduction additive reduces the quantity of airbornedust particles having a size of less than or equal to 10 microns to lessthan 50% of the quantity that would be generated without the additive.In certain embodiments, the quantity of airborne dust particles isreduced by at least 75% compared to a mixture without the additive. Mostpreferably, the level of airborne dust is reduced by more than 90%. Inone embodiment, the quantity of airborne particles generated by sandingthe hardened joint compound of the present invention is less than 50mg/m³ and, in certain other embodiments, less than about 20 mg/m³. Thequantity of airborne particles generated by sanding the hardened jointcompound is preferably less than 20 mg/m³.

It is desirable that the dust reduction additive serve to suppress theformation of airborne particles without significantly interfering withthe desired characteristics of the joint compound. The present inventionin fact discloses a joint compound that has a synergistic combination ofimproved dust generation property, improved water resistance, andimproved adhesive property.

The joint compound formulations include a conventional filler materialand a binder material, such as a resin. The joint compound can alsoinclude a surfactant, which may or may not serve to suppress airbornedust formation, and a thickening agent. Prior to hardening, the jointcompound preferably includes a sufficient amount of water to form amud-like spreadable material which can be applied to the wall surface.The present invention further provides an additive which can be admixedwith conventional joint compounds to reduce the quantity of dustgenerated during sanding. The dust reduction additive can be used withboth drying-type (i.e. ready-mixed) or setting-type joint compounds.

The present invention also provides a method of reducing the quantity ofairborne dust generated by sanding a fully hardened joint compound whichincludes mixing a sufficient quantity of a dust reduction additive withthe joint compound prior to applying the joint compound to a wallsurface.

In some embodiments, the joint compound can comprise the dust reductionadditive and can have a contact angle of about 90 to about 130 degrees,a pH below 12, and a Cobb value of about 1.0 to about 1000 grams persquare meter.

In some embodiments, the joint compound can further comprise a rheologymodifier, a binder, a thickener, and a filler. In some embodiments, thejoint compound can further comprise calcium carbonate, or cristobalite,or a micro-roughened filler, or gypsum, or mica, or clay, or thickener,or a latex binder, or talc, or perlite, or expanded perlite, orcombinations thereof. In some embodiments, the joint compound cancomprise the dust reducing additive powder (CPWB microstructure),wherein the CPWB microstructure in its emulsion form can comprise water,polyvinyl alcohol, wax, or montan wax, or synthetic wax, or combinationsthereof, a base, and a dispersant.

This invention also relates to a dust reducing additive powder preparedfrom CPWB microstructure, the CPWB microstructure comprises waxchemically tethered to an emulsifier such as montan wax, a waxcontaining organic acids and/or esters, or an emulsifier containing amixture of organic acids such as stearic acid and/or esters, orcombinations thereof; the emulsifier, in turn, chemically tethered to astabilizer polyvinyl alcohol, wherein the PVOH forms an encapsulationaround wax that is micro-crystalline-wax.

In some embodiments, the joint compound shows a peak airborne dustproduction being reduced from about 10% to about 98% compared to thecommercially available joint compound dust reduction additive.

In some embodiments, the joint compound can have a pH below 9. In someembodiments, the joint compound can have a contact angle of about 60 toabout 130 degrees. In some embodiments, the joint compound can begenerally hydrophobic and can have a contact angle of about 110 to about130 degrees. In some embodiments, the joint compound can have a Cobbvalue of about 1.0 to about 1000 grams per square meter. In someembodiments, the joint compound can have a Cobb value of about 65 gramsper square meter.

In some embodiments, the joint compound can further comprise a rheologymodifier, a binder, a thickener, and a filler. In some embodiments, thejoint compound can further comprise calcium carbonate, or cristobalite,or a micro-roughened filler, or gypsum, or mica, or clay, or thickener,or a latex binder, or talc, or perlite, or expanded perlite, orcombinations thereof.

In some embodiments, the joint compound can comprise the DRA powderprepared from a wax emulsion stabilized with polyvinyl alcohol. In someembodiments, the joint compound can comprise the DRA powder preparedfrom a wax emulsion comprising synthetic wax. In some embodiments, thejoint compound can comprise the DRA powder prepared from a wax emulsion,the wax emulsion can comprise synthetic wax including polyethyleneglycol or methoxypolyethylene glycol, or both polyethylene glycol andmethoxypolyethylene glycol.

In some embodiments, the joint compound can comprise the DRA powderprepared from a wax emulsion and silicones, or siloxanes, orsiliconates, or fluorinated compounds, or stearates, or combinationsthereof.

In some embodiments, the joint compound can comprise the DRA powderprepared from a micro-crystalline wax emulsion, the micro-crystallinewax emulsion can be formed by mixing a combination of water, polyvinylalcohol, and micro-crystalline wax, or montan wax, or synthetic wax, orcombinations thereof.

In some embodiments, the joint compound can comprise the DRA powderprepared from microcrystalline-wax emulsion and silicones, orsiliconates, or fluorinated compounds, or stearates, or combinationsthereof. In some embodiments, the silicones, siliconates, fluorinatedcompounds, or stearates can be selected from the group consisting ofmetal siliconate salts, potassium siliconate, poly hydrogen methylsiloxane, polydimethyl siloxane, stearate-based salts, and combinationsthereof.

In some embodiments, the joint compound can comprise the DRA powderprepared from a microcrystalline-wax emulsion and optionally at leastone thickener, preferably a cellulose ether based thickener.

As discussed previously, lower dust production in using joint compoundsmakes the joint compound more amenable to a worker's health and safety,for example less irritation to eyes, nose, and throat, and in long termminimization of respiratory diseases and lung damage. Clearly, a cleanworking environment is more preferred by the workers, which would resultin improved productivity and fewer breaks for fresh air by the workers.It also would result in faster clean-up of the job site and of theturnaround time. The current low-dust products in the markets havehigher costs in addition to creating increased sandpaper clogging, whichresults in frequent sandpaper changing and higher incremental costs.

The present invention relates to a technology based on proprietaryencapsulation of low dusting micro-crystalline wax. The encapsulatedparticles of the present invention have excellent adhesive properties.In some embodiments, the binder content can be reduced, which can thenlower the formulation cost of the joint compound. This inventionprovides a significant dust reduction at a very low dosage and with nopeculiar odor or any noticeable effect on the other performanceproperties of the joint compound. It is a low-cost (may be even acost-neutral) alternative to the existing formulations and can beincorporated into any class of joint compounds. Another advantage of thelow dust additive of the present invention is it helps reduce therequirement of the latex binder in the joint compounds to the extentthat in some embodiments of the joint compound no latex binder needs tobe added.

This invention relates to a method of using joint compound compositionthat has low-dust property and optionally improved adhesive propertyand/or improved water resistance property;

-   -   said method comprising:    -   (I) applying said composition to a joint between adjacent        wallboard panels;    -   (II) allowing said composition to dry; and    -   (III) sanding said dried composition;    -   wherein said joint compound composition comprises a dust        reduction additive emulsified powder comprising        colloidally-protected wax-based (CPWB) microstructures.

This invention also relates to the method described above, wherein saiddust reduction additive emulsified powder comprises said CPWBmicrostructure comprising:

(A) a wax core;

-   -   wherein said wax core comprises a micro-crystalline wax        component and/or a non-micro-crystalline wax component,    -   wherein said micro-crystalline wax component comprises at least        one linear alkane wax defined by the general formula        C_(n)H_(2n+2), where n ranges from 13-80,    -   wherein said non-micro-crystalline wax component comprises at        least one wax selected from the group consisting of animal-based        wax, plant-based wax, mineral wax, synthetic wax, a wax        containing organic acids and/or esters, anhydrides, an        emulsifier containing a mixture of organic acids and/or esters,        and combinations thereof; and

(B) a polymeric shell;

-   -   wherein said polymeric shell comprises at least one polymer        selected from polyvinyl alcohol, polyvinyl alcohol copolymers,        polyvinyl alcohol terpolymers, polyvinyl acetate, polyvinyl        acetate copolymers, polyvinyl acetate terpolymers, cellulose        ethers, polyethylene oxide, polyethyleneimines,        polyvinylpyrrolidone, polyvinylpyrrolidone copolymers,        polyethylene glycol, polyacrylamides and poly        (N-isopropylamides), pullulan, sodium alginate, gelatin,        starches, and combinations thereof.

In one embodiment, this invention relates to the methods described abovewherein said polymeric shell comprises polyvinyl alcohol. In yet anotherembodiment, this invention relates to a methods described above, whereinsaid dust-reduction additive emulsified powder, which is made from anemulsion, wherein said emulsion further comprises a base; and adispersant. In one embodiment, this invention relates to a methodsdescribed above, wherein the weight of said dust reduction additiveemulsified powder is in the range of from about 0.1% to about 20% byweight of said joint compound composition. In another embodiment, thisinvention relates to a methods described above, wherein the quantity ofdust generated upon sanding of said low-dust joint compound compositionis reduced at least by 5%. In yet another embodiment, this inventionrelates to a methods described above, wherein the quantity of dustgenerated upon sanding of said low-dust joint compound composition isreduced at least by 80%.

This invention also relates to a method for reducing the quantity ofdust generated by a joint-compound composition, said method comprisingthe steps of:

-   -   (I) providing a joint-compound composition comprising a filler,        a first water, binder, and at least one of a defoamer, wetting        agent, preservative, fungicide, thickener, non-leveling agent,        surfactant, and a solvent; and    -   (II) subsequently adding a sufficient quantity of a        dust-reduction additive emulsified powder as described        previously to said joint-compound composition to reduce the        quantity of dust generated by sanding the hardened        joint-compound composition by at least 5%.

In one embodiment, this invention relates to the method described abovefor reducing the quantity of dust generated by a joint-compound asrecited above, wherein the quantity of dust generated by sanding saidhardened drywall joint-compound is reduced by at least 80%. In anotherembodiment, this invention relates to the method described above forreducing the quantity of dust generated by a joint-compound as recitedabove, wherein said joint compound composition has a contact angle ofabout 60° to about 150°; and/or wherein said joint compound compositionhas a Cobb value of about 5.0 to about 100 g/m².

In one embodiment, this invention relates to a low-dust joint compound,further comprising at least one component from a filler; a binder; athickener; a non-leveling agent; a preservative; a rheology modifier;and a surfactant.

In another embodiment, this invention relates to the low-dust jointcompound composition as recited above, wherein:

-   -   said filler is selected from calcium carbonate (CaCO₃), calcium        sulfate dihydrate (CaSO₄ 2H₂O), calcium sulfate hemihydrate        (CaSO₄-1/2H₂O), glass micro bubbles, mica, perlite, talc,        limestone, pyrophyllite, silica, diatomaceous earth,        cristobalite, a micro-roughened filler, clay, and combinations        thereof;    -   said binder is selected from polyvinyl acetate, polyvinyl        alcohol, ethylene vinyl acetate co-polymer, vinylacrylic        copolymer, styrenebutadiene, polyacrylamide, acrylic polymers,        latex, natural starch, synthetic starch, casein, and        combinations thereof;    -   said thickener is selected from methyl cellulose, hydroxypropyl        cellulose, hydroxypropyl methyl cellulose, hydroxyethyl        cellulose, hydroxyethyl methyl cellulose, hydroxyethyl        hydroxypropyl cellulose, ethylhydroxyethyl cellulose, sodium        carboxymethyl cellulose, and combinations thereof; and    -   said non-leveling agent is selected from attapulgite clay,        bentonite, illite, kaolin, sepiolite, clays mixed with starches,        and combinations thereof.

In yet another embodiment, this invention relates to the low-dust jointcompound composition as recited above, wherein the weight of said dustreduction additive is in the range of from about 0.1% to about 20% byweight of said low-dust joint compound composition. In one embodiment,this invention relates to the low-dust joint compound composition asrecited above wherein, the weight of said dust reduction additive is inthe range of from about 0.1% to about 10% by weight of said low-dustjoint compound composition. In yet another embodiment, this inventionrelates to the low-dust joint compound composition as recited above,wherein the peak air-borne dust generation of said low-dust jointcompound is less than 100 mg/m³.

In another embodiment, this invention relates to the low-dust jointcompound composition as recited above, wherein the quantity of dustgenerated upon sanding of said low-dust joint compound composition isreduced at least by 5%. In one embodiment, this invention relates to thelow-dust joint compound composition as recited above, wherein thequantity of dust generated upon sanding of said low-dust joint compoundcomposition is reduced at least by 80%. In yet another embodiment, thisinvention relates to the low-dust joint compound composition as recitedabove, further comprising at least one component from a silicone, asiliconate, a fluorinated compound, a stearate, or a combinationthereof.

In another embodiment, this invention relates to the low-dust jointcompound composition as recited above, wherein the silicones,siliconates, fluorinated compounds, or stearates are selected from thegroup consisting of metal siliconate salts, potassium siliconate, polyhydrogen methyl siloxane, polydimethyl siloxane, stearate-based salts,and combinations thereof.

This invention further relates to a method of using said low-dust jointcompound composition as recited above, said method comprising:

-   -   (I) applying said composition to a joint between adjacent        wallboard panels;    -   (II) allowing said composition to dry; and    -   (III) sanding said dried composition.

This invention also relates to the method described above, for reducingthe quantity of dust generated by a joint-compound composition, saidmethod comprising the steps of:

-   -   (I) providing a joint-compound composition comprising a filler,        a first water, binder, and at least one of a defoamer, wetting        agent, preservative, fungicide, thickener, non-leveling agent,        surfactant, and a solvent; and    -   (II) subsequently adding a sufficient quantity of a        dust-reduction additive powder as described previously to said        joint-compound composition to reduce the quantity of dust        generated by sanding the hardened joint-compound composition by        at least 5%.

This invention relates to methods described above for reducing thequantity of dust generated by a joint-compound as recited in Claim 21,wherein the quantity of dust generated by sanding said hardened drywalljoint-compound is reduced by at least 80%.

This invention further relates to methods described above wherein saidjoint compound composition has a contact angle of about 60° to about150°; and/or wherein said joint compound composition has a Cobb value ofabout 5.0 to about 100 g/m².

This invention further relates to a low-dust joint compound compositioncomprising a dust reduction additive emulsified powder as describedpreviously.

This invention also relates to the low-dust joint compound compositionas recited above, further comprising at least one component from afiller; a binder; a thickener; a non-leveling agent; a preservative; arheology modifier; and a surfactant.

This invention also relates to the low-dust joint compound compositionas recited above, wherein:

-   -   said filler is selected from calcium carbonate (CaCO₃), calcium        sulfate dihydrate (CaSO₄ 2H₂O), calcium sulfate hemihydrate        (CaSO₄-1/2H₂O), glass micro bubbles, mica, perlite, talc,        limestone, pyrophyllite, silica, diatomaceous earth,        cristobalite, a micro-roughened filler, clay, and combinations        thereof;    -   said binder is selected from polyvinyl acetate, polyvinyl        alcohol, ethylene vinyl acetate co-polymer, vinylacrylic        copolymer, styrenebutadiene, polyacrylamide, acrylic polymers,        latex, natural starch, synthetic starch, casein, and        combinations thereof;    -   said thickener is selected from methyl cellulose, hydroxypropyl        cellulose, hydroxypropyl methyl cellulose, hydroxyethyl        cellulose, hydroxyethyl methyl cellulose, hydroxyethyl        hydroxypropyl cellulose, ethylhydroxyethyl cellulose, sodium        carboxymethyl cellulose, and combinations thereof; and    -   said non-leveling agent is selected from attapulgite clay,        bentonite, illite, kaolin, sepiolite, clays mixed with starches,        and combinations thereof.

This invention further relates to the low-dust joint compoundcomposition as recited previously, wherein the weight of said dustreduction additive is in the range of from about 0.1% to about 20% byweight of said low-dust joint compound composition.

This invention also relates to the low-dust joint compound compositionas recited previously, wherein the weight of said dust reductionadditive is in the range of from about 0.1% to about 10% by weight ofsaid low-dust joint compound composition.

This invention further relates to the low-dust joint compoundcomposition as recited previously, wherein the peak air-borne dustgeneration of said low-dust joint compound is less than 100 mg/m³.

Furthermore, this invention relates to the low-dust joint compoundcomposition as recited previously, wherein the quantity of dustgenerated upon sanding of said low-dust joint compound composition isreduced at least by 5%.

This invention also relates to the low-dust joint compound compositionas recited previously, wherein the quantity of dust generated uponsanding of said low-dust joint compound composition is reduced at leastby 80%.

Furthermore, this invention relates to the low-dust joint compoundcomposition as recited in previously, further comprising at least onecomponent from a silicone, a siliconate, a fluorinated compound, astearate, or a combination thereof.

This invention also relates to the low-dust joint compound as recitedpreviously, wherein the silicones, siliconates, fluorinated compounds,or stearates are selected from the group consisting of metal siliconatesalts, potassium siliconate, poly hydrogen methyl siloxane, polydimethylsiloxane, stearate-based salts, and combinations thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosed aspects will hereinafter be described in conjunction withthe appended drawings, provided to illustrate and not to limit thedisclosed aspects, wherein like designations denote the elements.

FIG. 1 illustrates a schematic of unitary wax particle that has beenstabilized in the colloidal dispersion.

FIG. 2 illustrates a simple schematic process describing the method ofpowderizing the CPWB microstructure dispersions.

FIG. 3 illustrates a wall having an example embodiment of the disclosedjoint compound applied thereon.

FIG. 4 shows the test enclosure used to sand test specimens and measurethe quantity of airborne dust particles generated.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The terms “approximately”, “about”, and “substantially” as used hereinrepresent an amount close to the stated amount that still performs adesired function or achieves a desired result. For example, the terms“approximately”, “about”, and “substantially” may refer to an amountthat is within less than 10% of, within less than 5% of, within lessthan 1% of, within less than 0.1% of, and within less than 0.01% of thestated amount.

General Embodiments

Embodiments of the present disclosure provide a dust reduction additive(“DRA”) powder comprising colloidally-protected, crystalline wax-based(“CPWB”) microstructures. Alternatively, the powder is also called“emulsified powder” or “DRA emulsified powder.” In another embodiment,the present invention relates to the process of preparing such dustreduction additive powders that also impart improved adhesive propertiesto the joint compound to which they are added, thereby lowering thebinder requirement of the joint compound. The emulsified powder improvesnot only the dust reduction of the joint compound but also provides bondstrength and adhesion of the joint compound to the substrate (e.g.,wallboard and/or joint tape).

In another embodiment, the present invention relates to the process ofpreparing such dust reduction additives.

Dust reduction additive refers to any ingredient capable of preventing,minimizing, suppressing, reducing, or inhibiting the formation ofparticles capable of becoming airborne. The expressions “airborneparticles” or “airborne dust particles” refer to fine particlesgenerated during the sanding or abrading of the compound which arecapable of being carried by or through the air. Wall repair compoundrefers generally to compositions useful for filling and repairingcracks, holes, and other imperfections in surfaces such as drywall,wood, plaster, and masonry. Wall repair compounds include interiorfinishing and patch compounds such as joint compound, spacklingcompound, wood fillers, plasters, stucco, and the like. The jointcompound can also include a thickener, and other materials found inconventional joint compounds. While the disclosure infra describes theDRA powder of the present invention in the context of a joint compound,the DRA powder can also be used with other wall-repair compounds.

The present invention also relates to low-dust joint compoundscomprising the dust reduction additive powder and methods for preparingsuch low-dust joint compounds. By “low-dust joint compound” is meant ajoint compound comprising DRA powder comprising wax, in which the dustformation in form of airborne particles is lower than the same jointcompound not comprising the DRA powder.

According to the present invention, there are provided joint compoundcompositions suitable for filling and repairing cracks, holes, or otherimperfections in a wall surface, such as the joints between adjacentwallboard panels. The compositions of the present invention include adust reduction additive combined with conventional wall repair compoundmaterials including a filler and/or, a binder, and/or a thickener toform a low dust wall repair compound.

In addition to providing a low-dust property, the joint compoundcompositions of the present invention, in some embodiments, also provideadhesive and water-repellent properties to the joint compound to whichit is added.

The joint compound may be used to create a low-dust barrier at walljoints, as well as at holes, such as nail holes, through a wall, therebyreducing the dust generated during processing of the joint compound andpreventing moisture from passing through the walls. The joint compoundmay be used, for example, in construction of houses or commercialbuildings.

In one embodiment, the joint compound comprises the dust reducingadditive powder prepared from an emulsion comprising an activated montanand polyvinyl alcohol-stabilized wax (for example, microcrystalline-wax)described further below. In another embodiment, the joint compoundcomprises the dust reduction additive that comprises micro-crystallinewax described further below. The resulting dried joint compound surfacecan exhibit a low-dust environment and in some embodiments, even a highcontact angle. Further, the disclosed joint compound formed from apowder comprising the wax emulsion can avoid deleterious effects on keydesirable performance properties of the joint compound such as adhesion.

In accordance with a characterizing feature of the present invention,the joint compound comprises the DRA which minimizes the quantity ofairborne particles generated, for example, during sanding of thehardened joint compound. The additive generally comprises less than 20%of the joint compound total wet weight. More preferably, the dustreduction additive comprises between about 0.1% and about 10% of thejoint compound by wet weight percent and, most preferably, between about0.5% and about 5% In one embodiment, the DRA is selected from any one ofthe following weight percentages: 0.1, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10,11, 12, 13, 14, 15, 16, 17, 18, 19, and 20.

The weight percentage of DRA powder in the joint compound can be anynumber within the range defined by any two numbers above, including theendpoints. The dust reduction additive of the present invention isdescribed in detail infra.

Many ingredients have been found to effectively reduce the quantity ofairborne particles generated when sanding the joint compound includingoils such as animal, vegetable, and mineral oils (saturated andunsaturated), and oils derived from petroleum, pitch, natural andsynthetic waxes, micro-crystalline-wax, solvents which evaporate slowerthan water, terpenes, glycols, surfactants, and mixtures thereof.However, the CPWB microstructure based DRA powder or themicro-crystalline wax based DRA powder unlock the synergistic effect ofthe three desired properties in the joint compound, namely: dustreducing property, water-repellency, and adhesion.

While the manner by which each additive serves to suppress the formationof particles capable of becoming airborne is not fully understood, somegeneral observations have been made. It is possible that the dustreduction additive may cause the dust particles to agglomerate or sticktogether, thereby forming large heavy particles which tend not to becomeor remain airborne. The invention, however, is not intended to belimited to any particular mechanism.

Duct Reducing Additive Powder Definitions

For the purposes of this invention, a “colloidal dispersion” is adispersion of a discontinuous phase in a continuous phase, comprisingcolloidally-protected micro-crystalline wax-based microstructures.

By “wax” is meant any naturally occurring or synthetically occurringwax. It also includes blends or mixtures of one or more naturallyoccurring and/or synthetically occurring waxes. Those of animal origintypically consist of wax esters derived from a variety of carboxylicacids and fatty alcohols. The composition depends not only on species,but also on geographic location of the organism. Because they aremixtures, naturally produced waxes are softer and melt at lowertemperatures than the pure components. Waxes are further discussedinfra.

In one embodiment, the wax is micro-crystalline wax. In anotherembodiment, the wax is paraffin wax.

Micro-Crystalline Wax

Generally, two chemically different waxy materials are extracted fromcrude oil: (1) paraffin wax or macro-wax; and (2) micro-crystalline-wax.Micro-crystalline wax is a refined mixture of solid, saturated aliphatichydrocarbons. It is characterized by a higher molecular weight branchedmolecular structure, longer hydrocarbon chains, and higher naphthenichydrocarbon content, compared to the paraffin wax that contains mostlyunbranched alkanes.

The micro-crystalline wax crystal structure is much finer than paraffinwax, which directly impacts many of the physical properties. Typicalmicro-crystalline wax crystal structure is small and thin, making themmore flexible than paraffin wax. The fine crystal structure also enablesmicro-crystalline wax to bind solvents or oil, and thus prevent thesweating-out of compositions. Also, the micro-crystalline wax contains ahigher amorphous content compared to the paraffin wax.

Micro-crystalline waxes are produced by de-oiling heavy distillates suchas petrolatum during petroleum refining. This by-product is thende-oiled at a wax refinery. Depending on the end use and desiredspecification, the product then may have its odor removed and colorremoved.

Micro-crystalline-waxes are tougher, more flexible and generally higherin melting point than paraffin wax. They are generally darker, moreviscous, denser, tackier and more elastic than paraffin waxes, and havea higher molecular weight and melting point. The elastic and adhesivecharacteristics of micro-crystalline waxes are related to theirnon-straight chain components.

Micro-crystalline waxes when produced by wax refiners are typicallyproduced to meet a number of ASTM specifications. These include congealpoint (ASTM D938), needle penetration (D1321), color (ASTM D6045), andviscosity (ASTM D445). Micro-crystalline waxes can generally be put intotwo categories: “laminating” grades and “hardening” grades. Thelaminating grades typically have a melt point of 140-175 F (60-80 C) andneedle penetration of 25 or above. The hardening grades will range fromabout 175-200 F (80-93 C), and have a needle penetration of 25 or below.Color in both grades can range from brown to white, depending on thedegree of processing done at the refinery level.

Micro-crystalline wax is often used in making of tire and rubber,candles, adhesives, corrugated board, cosmetics, and castings.Micro-crystalline-waxes are excellent materials to use when modifyingthe crystalline properties of paraffin wax. The micro-crystalline waxhas significantly more branching of the carbon chains that are thebackbone of paraffin wax. This is useful when some desired functionalchanges in the paraffin are needed, such as flexibility, higher meltpoint, and increased opacity. They are also used as slip agents inprinting ink.

TABLE 1 Comparison of Micro-crystalline and Paraffin Waxes Paraffin-WaxMicro-crystalline-Wax Mainly unbranched alkanes Mainly branched alkanesCrystalline Amorphous Brittle Malleable Translucent Opaque Low melting(48 to 70° C.) Higher melting (54 to 95° C.)

By “emulsion” or “wax-based emulsion” or “micro-crystalline-wax-basedemulsion” is meant an aqueous colloidally occurring dispersion ormixture in a liquid or paste-like form comprising wax materials, whichhas both the discontinuous and the continuous phases, preferably asliquid. For example, an aqueous micro-crystalline wax system can eitherbe a general colloid, or it can be an emulsion (which is a type ofcolloid), depending on the melt temperature of the emulsifiedmicro-crystalline wax versus the use temperature. In the disclosurebelow, the term “emulsion” is used. It should be noted, however, that acolloidal dispersion is also within the scope of the present invention.

By “colloidally-protected wax-based microstructure” (CPWBmicrostructure) is meant a colloidal dispersion or emulsion, wherein themicrostructure is colloidally protected with a wax or a lower fractionhydrocarbon core. The microstructure can exist in a dispersion oremulsion form.

By “colloidally-protected micro-crystalline wax-based microstructure”(CMWB microstructure) is meant a colloidal dispersion or emulsion,wherein the microstructure is colloidally protected with a wax or alower fraction hydrocarbon core. The microstructure can exist in adispersion or emulsion form.

Colloidally-Protected-Wax-Based Microstructures

This invention relates to DRA powder that comprise CPWB microstructuresThey have been alternatively called “CPWB microstructure based DRAemulsion powder,” or “DRA powder,” or “DRA powder comprising CPWBmicrostructures.” CPWB microstructures have a wax core and film orcasing of polymeric moieties which are adhered to the core via secondaryforces such as hydrogen bonding or Van Der Waals forces as opposed to amechanical shell over a core in a classical core-shell structure. CPWBmicrostructures are described in detail below. In the p DRA powdercomprising the CPWB microstructures, the core may be fully or partiallyencapsulated, in that the colloidal shell is not a physical shell likethat of a typical core-shell structure. The DRA powder comprising CPWBmicrostructure provides low-dust property, water-repellency, andadhesion property to the joint compound to which it is added.

CPWB Microstructure Shell

The polymers selected for the shell of the CPWB microstructures forlow-dust joint compound applications are one or more of the following:

-   -   Polyvinyl alcohol and copolymers, cellulose ethers, polyethylene        oxide, polyethyleneimines, polyvinylpyrrolidone, and copolymers,        polyethylene glycol, polyacrylamides and poly        (N-isopropylamides, pullulan, sodium alginate, gelatin, and        starches. Polyvinyl alcohol and copolymers are preferred.

CPWB Microstructure Core

The core of the colloidally-protected wax-based microstructures can be awax, for example, a microcrystalline-wax, or a paraffin wax as definedpreviously. This invention also envisions a blend ofmicro-crystalline-wax and paraffin-wax, wherein themicro-crystalline-wax is in the range of 0.1% to 99.9% by weight of thecombined content of the microcrystalline-wax and the paraffin-wax. Inone embodiment, the content of microcrystalline-wax in such a blend canbe any one of the following numbers or an inclusive range defined by anytwo numbers expressed in percentage: 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7,0.8, 0.9, and 1. In another embodiment, the content ofmicro-crystalline-wax in such a blend can be any one of the followingnumbers or an inclusive range defined by any two numbers expressed inpercentage: 2, 3, 4, 5, 6, 7, 8, 9, and 10. In yet another embodiment,the content of micro-crystalline-wax in such a blend can be any one ofthe following numbers or an inclusive range defined by any two numbersexpressed in percentage: 10, 145, 20, 25, 30, 35, 40, 45, 50, 55, 60,65, 70, 75, 80, 85, 90, 95, and 100. In a further embodiment, thecontent of micro-crystalline-wax in such a blend can be any one of thefollowing numbers or an inclusive range defined by any two numbersexpressed in percentage: 95, 96, 97, 98, and 99. In another embodiment,the content of the micro-crystalline wax in such a blend can be any oneof the following numbers or an inclusive range defined by any twonumbers expressed in percentage: 99, 99.1, 99.2, 99.3, 99.4, 99.5, 99.6,99.7, 99.8 and 99.9.

In one embodiment, preferably the core comprises themicrocrystalline-wax in a substantial amount, for example, greater than90%.

The melting point of core wax is lower than the melting point of thecolloidally-protective polymeric shell.

Some embodiments of the present invention envision micro-crystalline waxthat comprises branched structures as well as a blend or mixture oflinear and branched structures of the micro-crystalline-wax. Thisinvention also embodies mixtures or blends of waxes with two or morecarbon numbers that may either be linear, branched, or blends of linearand branched structures. For example, a wax could be a mixture of C₁₅linear and C₂₀ linear hydrocarbon alkane wax. In another example, thewax could be a mixture of C₁₆ linear and C₁₆ branched hydrocarbon alkanewax. In yet another example, the wax could be a mixture of C₁₅ linear,C₁₆ linear, and C₂₀ branched. In yet another example, the wax could be amixture of C₁₈ linear, C₁₈ branched.

Waxes usable as core in the CPWB microstructure-based DRA emulsion ofthe present invention are described.

Waxes

For the purposes of the present invention, waxes include naturallyoccurring waxes and synthetic waxes. Naturally occurring waxes includeplant based waxes, animal waxes, and mineral waxes. Synthetic waxes aremade by physical or chemical processes.

Examples of plant based waxes include mixtures of unesterifiedhydrocarbons, which may predominate over esters. The epicuticular waxesof plants are mixtures of substituted long-chain aliphatic hydrocarbons,containing alkanes, alkyl esters, sterol esters, fatty acids, primaryand secondary alcohols, diols, ketones, aldehydes, aliphatic aldehydes,primary and secondary alcohols, β-diketones, triacylglycerols, and manymore. The nature of the other lipid constituents can vary greatly withthe source of the waxy material, but they include hydrocarbons. Specificexamples of plant wax include Carnauba wax, which is a hard wax obtainedfrom the Brazilian palm Copernicia prunifera, which contains the estermyricyl cerotate. Other plant based waxes include candelilla wax,ouricury wax, jojoba plant wax, bayberry wax, Japan wax, sunflower wax,tall oil, tallow wax, rice wax, and tallows.

Animal wax includes beeswax as well as waxes secreted by other insects.A major component of the beeswax used in constructing honeycombs is theester myricyl palmitate which is an ester of triacontanol and palmiticacid. Spermaceti occurs in large amounts in the head oil of the spermwhale. One of its main constituents is cetyl palmitate, another ester ofa fatty acid and a fatty alcohol. Lanolin is a wax obtained from wool,consisting of esters of sterols. Other animal wax examples includelanocerin, shellac, and ozokerite.

Examples of mineral waxes include montan wax, micro-crystalline wax andparaffin wax. Although many natural waxes contain esters, paraffin waxesare hydrocarbons, mixtures of alkanes usually in a homologous series ofchain lengths. Montan wax is a fossilized wax extracted from coal andlignite. It is very hard, reflecting the high concentration of saturatedfatty acids/esters and alcohols. Montan wax includes chemical componentsformed of long chain alkyl acids and alkyl esters having chain lengthsof about 24 to 30 carbons. In addition, natural montan includes resinacids, polyterpenes and some alcohol, ketone and other hydrocarbons suchthat it is not a “pure” wax. The saponification number of montan, whichis a saponifiable wax, is about 92 and its melting point is about 80° C.Waxes comprising esters and/or acids may act as emulsifiers to theparaffins (waxes—micro-crystalline wax or paraffin wax, or a mixturethereof).

Synthetic waxes include waxes based on polypropylene, polyethylene, andpolytetrafluoroethylene. Other synthetic waxes are based on fatty acidamines, Fischer Tropsch, and polyamides, polyethylene and relatedderivatives. Some waxes are obtained by cracking polyethylene at 400° C.The products have the formula (CH₂)_(n)H₂, where n ranges between about50 and 100.

Also outside of the building products context, in addition to waxes thatoccur in natural form, there are various known synthetic waxes whichinclude synthetic polyethylene wax of low molecular weight, i.e.,molecular weights of less than about 10,000, and polyethylenes that havewax-like properties. Such waxes can be formed by direct polymerizationof ethylene under conditions suitable to control molecular weight.Polyethylenes with molecular weights in about the 2,000-4,000 range arewaxes, and when in the range of about 4,000-12,000 become wax resins.

Fischer-Tropsch waxes are polymethylene waxes produced by a particularpolymerization synthesis, specifically, a Fischer-Tropsch synthesis(polymerization of carbon monoxide under high pressure, high temperatureand special catalysts to produce hydrocarbon, followed by distillationto separate the products into liquid fuels and waxes). Such waxes(hydrocarbon waxes of micro-crystalline, polyethylene and polymethylenetypes) can be chemically modified by, e.g., air oxidation (to give anacid number of 30 or less and a saponification number no lower than 25)or modified with maleic anhydride or carboxylic acid. Such modifiedwaxes are more easily emulsified in water and can be saponified oresterified. Other known synthetic waxes are polymerized alpha-olefins.These are waxes formed of higher alpha-olefins of 20 or more carbonatoms that have wax like properties. The materials are very branchedwith broad molecular weight distributions and melting points rangingabout 54° C. to 75° C. with molecular weights of about 2,600 to 2,800.Thus, waxes differ depending on the nature of the base material as wellas the polymerization or synthesis process, and resulting chemicalstructure, including the use and type of any chemical modification.

Various types of alpha-olefin and other olefinic synthetic waxes areknown within the broad category of waxes, as are chemically modifiedwaxes, and have been used in a variety of applications, outside thewater-resistant wallboard area. They are of a wide variety and vary incontent and chemical structure. As noted above, water-resistantwallboard products generally use paraffin, paraffin and montan, or otherparaffinic or synthetic waxes as described above in the mentionedexemplary patent references. In one embodiment of the invention, the waxused for the preparation of the dispersion or emulsion is used in amicronized, pulverized form. U.S. Pat. Nos. 8,669,401 and 4,846,887 showexemplary micronization processes. Both these patents are incorporatedby reference herein as if fully set forth.

In one embodiment, the emulsifiers for this invention include montanwax, esters/acids, styrene-maleic anhydride, polyolefin maleicanhydride, or other anhydrides, carnauba wax, rice wax, sunflower wax.

Theory—CPWB Microstructures

Generally speaking, two scientific theories have been proposed toexplain the stability of CPWB microstructures that comprise the DRAemulsion materials of the present invention, namely, steric hindranceand electrostatic repulsion. Applicants do not wish to be bound by thesetheories, however. Applicants believe their invention relates towax-based dispersions that may or may not relate to the two theories. Itis possible that one or both theories or neither of the two may explainthe CPWB microstructures of the present invention.

FIG. 1 describes the particle model of a unitary wax particle that hasbeen stabilized in the colloidal dispersion. Applicants do not wish tobe bound by the theory of the unitary wax particle stabilized in thedispersion. According to this model, the hydrophobic hydrocarbon “tail”of the montan is embedded in the wax particle. The “head” of montan,which is hydrophilic is then tethered to polyvinyl alcohol. The firstmechanism by which many of the wax emulsions (colloidal dispersions) arestabilized is the steric hindrance mechanism. According to thismechanism, high molecular weight polymers (e.g. PVOH) are tethered tothe outer surface of a micro-crystalline wax particle and surround it.Due to steric hindrance, the PVOH molecules surrounding each waxparticle then prevent adjacent micro-crystalline wax particles fromcoalescing.

Alternatively, electrostatic repulsion helps with the stabilization ofthe colloidal dispersions. In this mechanism, the montan wax particle,which contains acid or ester groups (either inherently or mixed in), isfirst saponified with a base, converting the acid or ester groups tonegatively charged carboxylate moieties. Because of their polar nature,these negatively charged carboxylate moieties exist at the water/waxinterface, giving the surrounded wax particle a net negative charge.These negative charges on adjacent wax particles then constitute arepulsive force between particles that effectively stabilizes thedispersion (emulsion).

Thus, according to one model, as shown in FIG. 2, a wax particle isenclosed in a “web” of PVOH polymeric chains. This is not akin to ashell of a typical core-shell particle, but the PVOH loosely protects(colloidally protects) the wax particle. One could envision the waxparticle as a solid ball or a nucleus surrounded by polymeric chainslike strings.

In another embodiment, and as shown in FIGS. 3 and 4, the polymer, forexample PVOH, forms a shell like physical film or casing such as a film(PVOH is an excellent film former), the casing herein is based onsecondary forces of attraction, e.g., Van der Waals forces. Hydrogenbonding may also be one of the forces for the encapsulation of the PVOHof the wax particles. Applicants do not wish to be bound by this theory.However, the model does explain the wax particle with the PVOH casingover it. In the above examples, PVOH is used as an exemplary polymericsystem. However, other polymeric systems used herein, or theircombinations can also be used to prepare the colloidally-protectedmicro-crystalline wax-based microstructures.

Preparation of DRA Powder from CPWB Microstructures

As described in FIG. 2, in the first step, a colloidally-protected waxbased microstructure in an emulsion is prepared. The emulsion isprepared according to the specification for their use in variety ofapplications. For a general understanding of the method of making theexemplary wax emulsion, reference is made to the flow diagram in FIG. 2.As shown in 101, first the wax components may be mixed in an appropriatemixer device. Then, as shown in 102, the wax component mixture may bepumped to a colloid mill or homogenizer. As demonstrated in 103, in aseparate step, water, and any emulsifiers, stabilizers, or additives(e.g., ethylene-vinyl alcohol-vinyl acetate terpolymer) are mixed. Thenthe aqueous solution is pumped into a colloid mill or homogenizer in104. Steps 101 and 103 may be performed simultaneously, or they may beperformed at different times. Steps 102 and 104 may be performed at thesame time, so as to ensure proper formation of droplets in the emulsion.In some embodiments, steps 101 and 102 may be performed before step 103is started. Finally, as shown in 105, the two mixtures from 102 and 104are milled or homogenized to form an aqueous wax-based emulsion.

In the next step, said dispersion or emulsion is subjected to the dryingand powderization step. Drying can be accomplished by one or more of theknown drying methods such as freeze drying, vacuum drying, air drying,spray drying, atomization, evaporation, tray drying, flash drying, drumdrying, fluid-bed drying, oven drying, belt drying, microwave drying,lyophilization, and solar drying. Other known drying methods that maynot be listed herein, may also be used. In one embodiment, more than onemethod may be used to dry the colloidal dispersion.

Further as shown in FIG. 4, in the third step, optionally, the moisturecontent of the powder material may be adjusted to suit the use of thepowder in a particular application. In the next step, which also is anoptional step, the powder may be subjected to a further pulverizationprocess to provide for a specific particle size distribution of thepowder. Finally, the resulting powder is then blended with a basematerial in which the wax based colloidal dispersion or emulsion is tobe added to improve the properties of the base material, for example,its moisture repellency.

The powder resulting from step 2 in the process described above, mayhave an average particle size in the range of from about 1 micron toabout 1,000 micron. Clearly, the larger sized particles would beagglomerates of the smaller powder emulsion particles. Theoretically,the smallest particle will be a wax particle that is covered, forexample, by a hydrogen-bonded coating of stabilizing polymeric chainsof, for example, among other things, polyvinyl alcohol.

The average particle size of the powders of the present invention can beany one of the following average particle sizes, measured in microns:

-   -   1, 2, 3, 4, 5, 6, 7, 8, 9, . . . , 98, 99, 100, 101, 102, . . .        , 198, 199, 200, 201, 202, . . . , 298, 299, 300, 301, 302, . .        . , 398, 399, 400, 401, 402, . . . , 498, 499, 500, 501, 502, .        . . , 598, 599, 600, 601, 602, . . . , 698, 699, 700, 701, 702,        . . . , 798, 799, 800, 801, 802, . . . , 898, 899, 900, 901,        902, . . . , 998, 999, and 1000.

The average particle size can also be in a range that is determined byany two numbers recited above, which would include the endpoints of therange.

In one embodiment, the particle size of the powders of the presentinvention is also such that 10%, 50% and/or 90% of the particles byweight are less than the following average particle size, measured inmicrons:

-   -   1, 2, 3, 4, 5, 6, 7, 8, 9, . . . , 98, 99, 100, 101, 102, . . .        , 198, 199, 200, 201, 202, . . . , 298, 299, 300, 301, 302, . .        . , 398, 399, 400, 401, 402, . . . , 498, 499, 500, 501, 502, .        . . , 598, 599, 600, 601, 602, . . . , 698, 699, 700, 701, 702,        . . . , 798, 799, 800, 801, 802, . . . , 898, 899, 900, 901,        902, . . . , 998, 999, and 1000.

The average particle size can also be in a range that is determined byany two numbers recited above, which would include the endpoints of therange.

The present invention applies to wax-based colloidal dispersionformulations (including the CPWB microstructure based emulsionsdescribed previously) and compositions that are amenable to thepowderization process described herein. For example, the followingpatent references describe wax-based emulsions. These references are setforth as if full incorporated herein.

Several wax emulsion formulations are disclosed in U.S. Pat. No.5,437,722, which are incorporated by reference herein. It describes awater-resistant gypsum composition and wax emulsion therefore, whichincludes a paraffin hydrocarbon having a melting point of about 40° C.to 80° C., about 1 to 200 parts by weight montan wax per 100 parts ofthe paraffin hydrocarbon, and about 1 to 50 parts by weight polyvinylalcohol per 100 parts of the paraffin hydrocarbon.

U.S. Publication No. 2006/0196391 describes use of triglycerides inemulsions, and notes that the prior art has made use of petroleum waxesand synthetic waxes such as Fischer Tropsch and polyethylene waxes,which have been used for purposes similar to those of the invention ofPublication 2006/0196391 with mixed results.

In the building products area, U.S. Patent Publication No 2007/0181035A1 is directed to a composition for use in making medium densityfiberboard (MDF). The composition has a component for reducing surfacetension and improving dimensional stability for use in oriented strandboard and MDF. The surface tension agents are either fluorinatedhydrocarbon compounds of two to six carbons or alkoxylates of alkylphenols or alkylated acetylene diols. These materials are provided to acomposition having a combination of montan wax with other waxes,ammonium hydroxide for saponification, water and polyvinyl alcohol.Nonsaponifiable waxes may be used in this composition, includingparaffin and scale or slack wax (which is petroleum derived).Saponifiable waxes which may be used include Montan, petroleum wax, andvarious natural waxes.

U.S. Patent Publication No. 2007/0245931 A1 discloses use of alkylphenols in emulsions for water-proof gypsum board. The alkyl phenols arelong-chain hydrocarbon chains having a phenolated ring of 24-34 carbonchain lengths. The publication describes use of lignosulfonic acid, andmagnesium sulfate. The wax components can be combinations of paraffinand montan. The patent claims that the compositions are stable withoutthe use of starch as in prior U.S. Pat. No. 6,663,707 of the sameinventor. The wax used in the composition may be various commerciallyknown waxes having a melting point of from about 120° F. (48.9° C.) to150° F. (65.6° C.) with low volatility and a high molecular weight withcarbon chain lengths of 36 or higher. The hydrocarbon wax componentincludes waxes known in the field of gypsum slurries.

U.S. Pat. No. 6,890,976 describes an aqueous emulsion for gypsumproducts with hydrocarbon wax, polyolefin-maleic anhydride graft polymerand polyvinyl alcohol and/or acetate. The maleic-modified material isknown as FLOZOL®. The hydrocarbon wax can be paraffin or a polyethylenewax, maleated hydrocarbon wax or combinations thereof. The wax can alsobe a synthetic wax ester or an acid wax. The polyolefin-maleic anhydridegraft copolymer is a 50-500 carbon chain graft copolymer, which whenprovided to the wax emulsion is described as providing improved waterrepellency to a final gypsum product.

U.S. Patent Publication No. 2004/0083928 A1 describes a suspension,instead of an emulsion, of various waxes in water that is mixed directlywith gypsum. In describing the waxes, the suspensions can includepolyethylene wax, maleated hydrocarbons and other waxes as well as waxcombinations.

U.S. Pat. No. 7,192,909 describes use of polyolefin wax in anapplication outside the building products area, which is as a lubricantfor plastics processing, specifically for PVC. The waxes are describedas homopolymers and copolymers of various alpha-olefins that have beenmodified in a polar manner (oxidized) or grated with polar reagents.They can be used alone or in combination with other waxes, e.g. montanwaxes, fatty acid derivatives or paraffins.

DRA Powder from CPWB Microstructures

Exemplary emulsified powder comprising CPWB microstructure for use in,for example, as a dust reduction additive (and for water-resistance) ina joint compound are now described in greater detail, as follows.

In one embodiment, the emulsion comprising CPWB microstructures maycomprise water, a base, one or more waxes optionally selected from thegroup consisting of slack wax, montan wax, and wax, and a polymericstabilizer, such as ethylene-vinyl alcohol-vinyl acetate terpolymer orpolyvinyl alcohol. Further, carnauba wax, sunflower wax, tall oil,tallow wax, rice wax, and any other natural or synthetic wax oremulsifier containing organic acids and/or esters can be used to formthe wax emulsion.

Water may be provided to the emulsion, for example in amounts of about30% to about 60% by weight of the emulsion. The solids content of thewax emulsion is preferably about 40% to about 70% by weight of theemulsion. Other amounts may be used.

In some embodiments, a dispersant and/or a surfactant may be employed inthe wax emulsions. Optional dispersants, include, but are not limited tothose having a sulfur or a sulfur-containing group(s) in the compoundsuch as sulfonic acids (R—S(═O)2-OH) and their salts, wherein the Rgroups may be otherwise functionalized with hydroxyl, carboxyl or otheruseful bonding groups. In some embodiments, higher molecular weightsulfonic acid compounds such as lignosulfonate, lignosulfonic acid,naphthalene sulfonic acid, the sulfonate salts of these acids, andderivatized or functionalized versions of these materials are used inaddition or instead. An example lignosulfonic acid salt is Polyfon® Havailable from MeadWestvaco Corporation, Charleston, S.C. Otherdispersants may be used, such as magnesium sulfate, polycarboxylatetechnology, ammonium hepta molybdate/starch combinations, non-ionicsurfactants, ionic surfactants, zwitterionic surfactants and mixturesthereof, alkyl quaternary ammonium montmorillonite clay, etc. Similarmaterials may also be used, where such materials may be compatible withand perform well with the formulation components.

In one embodiment, a dispersant and/or surfactant may comprise about0.01% to about 5.0% by weight of the wax emulsion formulationcomposition, preferably about 0.1% to about 2.0% by weight of the waxemulsion formulation composition. Other concentrations may be used.

The wax component of the emulsion may include at least one wax which maybe slack wax, or a combination of montan wax and slack wax. The totalwax content may be about 30% to about 60%, more preferably about 30% toabout 40% by weight of the emulsion. Slack wax may be any suitable slackwax known or to be developed which incorporates a material that is ahigher petroleum refining fraction of generally up to about 20% byweight oil. In addition to, or as an alternative to slack wax, -waxes ofa more refined fraction are also useful within the scope of theinvention.

Suitable-waxes include waxes with melting points of from about 40° C. toabout 110° C., although lower or higher melting points may be used ifdrying conditions are altered accordingly using any techniques known oryet to be developed in the composite board manufacturing arts orotherwise. Thus, micro-crystalline waxes or less refined slack wax maybe used. Optionally, synthetic waxes such as ethylenic polymers orhydrocarbon types derived via Fischer-Tropsch synthesis may be includedin addition. The wax emulsion (from which the DRA powder is formed) canbe formed from slack wax, montan wax, micro-crystalline wax, carnaubawax, tall oil, sunflower wax, rice wax, and any other natural orsynthetic wax containing organic acids and/or esters, or combinationsthereof. For example, synthetic wax used in the joint compound maycomprise ethylenic polymers or hydrocarbon types, optionally derived viaFischer-Tropsch synthesis, or combinations thereof. Optionally, thesynthetic waxes can be added in concentrations ranging from about 0.1%to about 8% of the dry weight of the joint compound or from about 0.5%to about 4.0% of the dry weight of the joint compound. In someembodiments, the wax emulsion is stabilized by polyvinyl alcohol.

Montan wax, which is also known in the art as lignite wax, is a hard,naturally occurring wax that is typically dark to amber in color(although lighter, more refined montan waxes are also commerciallyavailable). Montan is insoluble in water, but is soluble in solventssuch as carbon tetrachloride, benzene and chloroform. In addition tonaturally derived montan wax, alkyl acids and/or alkyl esters which arederived from high molecular weight fatty acids of synthetic or naturalsources with chain lengths preferably of over 18 carbons, morepreferably from 26 to 46 carbons that function in a manner similar tonaturally derived montan wax are also within the scope of the inventionand are included within the scope of “montan wax” as that term is usedherein unless the context indicates otherwise (e.g., “naturallyoccurring montan wax”). Such alkyl acids are generally described asbeing of formula R—COOH, where R is an alkyl non-polar group which islipophilic and can be from 18 to more than 200 carbons. An example ofsuch a material is octacosanoic acid and its corresponding ester whichis, for example, a di-ester of that acid with ethylene glycol. The COOHgroup forms hydrophilic polar salts in the presence of alkali metalssuch as sodium or potassium in the emulsion. While the alkyl portion ofthe molecule gets embedded within the paraffin, the acid portion is atthe paraffin/aqueous medium interface, providing stability to theemulsion.

In some embodiments, the at least one wax component is made up of acombination of wax and montan wax or of slack wax and montan wax.Although it should be understood that varying combinations of such waxescan be used. When using montan wax in combination with one or more ofthe other suitable wax components, it is preferred that montan bepresent in an amount of about 0.1% to about 10%, more preferably about1% to about 4% by weight of the wax emulsion with the remaining wax orwaxes present in amounts of from about 30% to about 50%, more preferablyabout 30% to about 35% by weight of the wax emulsion.

In some embodiments, the wax emulsion includes polyvinyl alcohol (PVOH)of any suitable grade which is at least partially hydrolyzed. Thepreferred polyvinyl alcohol is at least 50%, and more preferably atleast 90%, and most preferably about 97-100% hydrolyzed polyvinylacetate. The PVA can be hydrolyzed to the extent defined by thepercentage numbers below: 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, and100.

The PVA can also be hydrolyzed up to the extent of a number that residesin the range defined by any two numbers above, including the endpoints.

Suitably, the polyvinyl alcohol is soluble in water at elevatedtemperatures of about 60° C. to about 95° C., but insoluble in coldwater. The hydrolyzed polyvinyl alcohol is preferably included in theemulsion in an amount of up to about 5% by weight, preferably 0.1% toabout 5% by weight of the emulsion, and most preferably about 2% toabout 3% by weight of the wax emulsion.

In some embodiments, the stabilizer comprises a polymer that is capableof hydrogen bonding to the carboxylate or similar moieties at thewater/wax interface. Polymers that fit the hydrogen-bonding requirementwould have such groups as hydroxyl, amine, and/or thiol, amongst others,along the polymer chain. Reducing the polymer's affinity for water (andthus, its water solubility) could be achieved by inserting hydrophobicgroups such as alkyl, alkoxy silanes, or alkyl halide groups into thepolymer chain. The result may be a polymer such as ethylene-vinylacetate-vinyl alcohol terpolymer (where the vinyl acetate has beensubstantially hydrolyzed). The vinyl acetate content may be between 0%to 15%. In some embodiments, the vinyl acetate content is between 0% and3% of the terpolymer chain. The ethylene-vinyl alcohol-vinyl acetateterpolymer may be included in the emulsion in an amount of up to about10.0% by weight, preferably 0.1% to about 5.0% by weight of theemulsion. In some embodiments, ethylene-vinyl alcohol-vinyl acetateterpolymer may be included in the emulsion in an amount of about 2% toabout 3% by weight of the wax emulsion. An example ethylene-vinylalcohol-vinyl acetate terpolymer that is available is the ExcevalAQ4104™, available from Kuraray Chemical Company.

The dust reduction additive powder comprising CPWB microstructures mayinclude a stabilizer material (e.g., PVOH, ethylene-vinyl alcohol-vinylacetate terpolymer as described above). The stabilizer may be soluble inwater at elevated temperatures similar to those disclosed with referenceto PVOH (e.g., about 60° C. up to about 95° C.), but insoluble in coldwater. The active species in the wax component (e.g., montan wax) may bethe carboxylic acids and esters, which may comprise as much as 90% ofthe wax. These chemical groups may be converted into carboxylatemoieties upon hydrolysis in a high pH environment (e.g., in anenvironment including aqueous KOH). The carboxylate moieties may act asa hydrophilic portion or “head” of the molecule. The hydrophilicportions can directly interface with the surrounding aqueousenvironment, while the rest of the molecule, which may be a lipophilicportion or “tail”, may be embedded in the hydrocarbon wax.

A stabilizer capable of hydrogen bonding to carboxylate moieties (e.g.,PVOH or ethylene-vinyl alcohol-vinyl acetate terpolymer as describedabove) may be used in the wax emulsion. The polar nature of thecarboxylate moiety may offer an optimal anchoring point for a stabilizerchain through hydrogen bonding. When stabilizer chains are firmlyanchored to the carboxylate moieties as described above, the stabilizermay provide emulsion stabilization through steric hindrance. In someembodiments the stabilizer may function as a gate-keeper for repellingmoisture. Decreasing the solubility of the stabilizer in water mayimprove the moisture resistance of the emulsified powder. For example,fully hydrolyzed PVOH may only dissolve in heated, and not cool, water.For another example, ethylene-vinyl alcohol-vinyl acetate terpolymer maybe even less water soluble than PVOH. The ethylene repeating units mayreduce the overall water solubility. Other stabilizer materials are alsopossible. For example, polymers with hydrogen bonding capability such asthose containing specific functional groups, such as alcohols, amines,and thiols, may also be used. For another example, vinyl alcohol-vinylacetate-silyl ether terpolymer can be used. An example vinylalcohol-vinyl acetate-silyl ether terpolymer is Exceval R-2015,available from Kuraray Chemical Company. In some embodiments,combinations of stabilizers are used.

In some embodiments, the emulsified powder comprising CPWBmicrostructures comprises a base. For example, the wax emulsion maycomprise an alkali metal hydroxide, such as potassium hydroxide or othersuitable metallic hydroxide, such as aluminum, barium, calcium, lithium,magnesium, sodium and/or zinc hydroxide. These materials may serve assaponifying agents. Non-metallic bases such as derivatives of ammonia aswell as amines (e.g., diethanolamine or triethanolamine) can also beused. Combinations of the above-mentioned materials are also possible.If included in the wax emulsion, potassium hydroxide is preferablypresent in an amount of 0% to 1%, more preferably about 0.1% to about0.5% by weight of the wax emulsion.

In some embodiments, an exemplary emulsified powder comprising CPWBmicrostructures comprises: about 30% to about 60% by weight of water;about 0.1% to about 5% by weight of a lignosulfonic acid or a saltthereof; about 0% to about 1% by weight of potassium hydroxide; about30% to about 50% by weight of wax selected from the group consisting ofparaffin wax, slack wax and combinations thereof; and about 0.1% toabout 10% montan wax, and about 0.1 to 5% by weight of ethylene-vinylalcohol-vinyl acetate terpolymer.

The emulsified powder comprising CPWB microstructures may furtherinclude other additives, including without limitation additionalemulsifiers and stabilizers typically used in wax emulsions, flameretardants, lignocellulosic preserving agents, fungicides, insecticides,biocides, sizing agents, fillers, binders, additional adhesives and/orcatalysts. Such additives are preferably present in minor amounts andare provided in amounts which will not materially affect the resultingcomposite board properties. Preferably no more than 30% by weight, morepreferably no more than 10%, and most preferably no more than 5% byweight of such additives are present in the wax emulsion.

Shown in the tables below are exemplary embodiments of a wax emulsioncomprising CPWB microstructures, although other quantities in weightpercent may be used.

TABLE 2 First Exemplary Embodiment of Dust Reduction Additive Emulsionfrom which DRA Powder is Made Raw Material Quantity in Weight PercentWater 58 Polyvinyl alcohol 2.70 Dispersant (Optional) 1.50Micro-crystalline Wax 34.30 Montan Wax 3.50 Biocide 0.02

TABLE 3 Second Exemplary Embodiment of Dust Reduction Additive Emulsionfrom which DRA Powder is Made Raw Material Quantity in Weight PercentWater 58.80 Polyvinyl alcohol 2.80 Diethanol Amine 0.04Micro-crystalline Wax 34.80 Montan Wax 3.50 Biocide 0.10

The emulsion comprising CPWB microstructures may be prepared using anyacceptable techniques known in the art or to be developed forformulating wax emulsions, for example, the wax(es) are preferablyheated to a molten state and blended together (if blending is required).A hot aqueous solution is prepared which includes any additives such asemulsifiers, stabilizers, etc., ethylene-vinyl alcohol-vinyl acetateterpolymer (if present), potassium hydroxide (if present) andlignosulfonic acid or any salt thereof. The emulsifiers may alsooptionally be mixed with the wax blend. The wax is then metered togetherwith the aqueous solution in appropriate proportions through a colloidmill or similar apparatus to form a wax emulsion, which may then becooled to ambient conditions if desired.

Some or all steps of the above method may be performed in open vessels.However, the homogenizer may use pressure in its application.

Advantageously in some embodiments, the emulsion, once formed, is cooledquickly. By cooling the emulsion quickly, agglomeration and coalescenceof the wax particles may be avoided.

In some embodiments the wax mixture and the aqueous solution arecombined in a pre-mix tank before they are pumped into the colloid millor homogenizer. In other embodiments, the wax mixture and the aqueoussolution may be combined for the first time in the colloid mill orhomogenizer. When the wax mixture and the aqueous solution are combinedin the colloid mill or homogenizer without first being combined in apre-mix tank, the two mixtures may advantageously be combined underequivalent or nearly equivalent pressure or flow rate to ensuresufficient mixing.

In some embodiments, once melted, the wax emulsion is quickly combinedwith the aqueous solution. While not wishing to be bound by any theory,this expedited combination may beneficially prevent oxidation of the waxmixture.

Low-Dust Joint Compound

Embodiments of the powders prepared from CPWB microstructures can beused to form many different low-dust products. For example, embodimentsof powders made from wax emulsion disclosed above can be used to form alow-dust joint compound. The joint compound can be used to cover,smooth, or finish gaps in boards, such as joints between adjacentboards, screw holes, and nail holes.

The joint compound can also be used for repairing surface defects onwalls and applying texture to walls and ceilings amongst numerous otherapplications. The joint compound can also be specially formulated toserve as a cover coat on cement and concrete surfaces. It can beparticularly useful in locations where there is high humidity, such asbathrooms, to prevent molding or other deleterious effects. In oneembodiment, the joint compound comprises a filler material.

While the above detailed description has shown, described, and pointedout features as applied to various embodiments, it will be understoodthat various omissions, substitutions, and changes in the form anddetails of the devices or algorithms illustrated can be made withoutdeparting from the spirit of the disclosure. For example, certainpercentages and/or ratios of component ingredients have been describedwith respect to certain example embodiments; however, other percentagesand ratios may be used. Certain process have been described, howeverother embodiments may include fewer or additional states. As will berecognized, certain embodiments of the inventions described herein canbe embodied within a form that does not provide all of the advantages,features and benefits set forth herein, as some features can be used orpracticed separately from others.

EXPERIMENTAL Examples 1-7—Preparation of the Powder from CPWBMicrostructures

Aqualite® 484 which is an emulsion from the Henry Company was spraydried to form particulate material from the emulsion. Aqualite® 484emulsion was added directly to a 300-gallon mixing tank with moderateagitation. The solids content of the emulsion was also calculated. Asolids result of 40.5% for the liquid was found. From the mixing tank,the emulsion was fed to the drying chamber of the spray drying equipmentthrough a two-fluid internal mix spray nozzle. The second fluid used wasair (at multiple pressures) to atomize the liquid into droplets. Fromthe drying chamber, powder was conveyed to a baghouse system. Powder wascollected directly from the baghouse and sifted through a 10-mesh screento remove any oversized powder agglomerates from the final product. Noinorganic flow agent was used during this trial. The product waspackaged in drums. The weight of each drum was dependent on how often adryer condition was changed. The powder samples were all tested formoisture content, particle size, and bulk density. Drying was performedat temperature between 115° F. and 140° F. (inlet) and 175° F. and 200°F. (outlet) and an atomization pressure of 120-130 psi. The meltingpoint of the product is 140° F. The moisture content of the finishedproduct was 1.26%. Particle size was measured for each test. The resultsare tabulated in Table 3. The D(10) particle size indicates the biggestaverage particle size that covers 10% of the material. D(50) indicatesthe average particle size below which 50% of the particles are found.

TABLE 3 Particle Size Measurement Final Particle Particle ParticleMoisture Size Size Size No. Content %* D(10) D(50) D(90) LBD/PBD 1. 1.2637.03 93.28 307.60 0.28/0.31 2. 0.78 39.58 109.90 367.50 0.29/0.32 3.0.69 46.01 150.80 533.70 0.30/0.35 4. 0.68 116.40 333.70 884.400.30/0.33 5. 2.37 80.00 264.40 660.90 0.31/0.35 6. 0.38 59.32 172.60441.10 0.26/0.29 7. 0.45 60.91 168.00 497.10 0.31/0.34 *Initial moisturecontent was 40.5% solids

This powder, for example, can be used as a dust reduction additive. Asdiscussed previously, embodiments of the disclosed CPWB microstructurepowder based dust reducing additive can be used to form a low-dust jointcompound. The joint compound can be used to cover, smooth, or finishgaps in boards, such as joints between adjacent boards, screw holes, andnail holes. The joint compound can also be used for repairing surfacedefects on walls and applying texture to walls and ceilings amongstnumerous other applications. The joint compound comprises a fillermaterial.

Fillers

Any conventional filler material can be used in the present invention.Suitable fillers include calcium carbonate (CaCO₃) and calcium sulfatedihydrate (CaSO₄ 2H₂O commonly referred to as gypsum) for ready mixedtype joint compounds, and calcium sulfate hemihydrate (CaSO₄-1/2H₂O) forsetting type joint compounds. The joint compound can also include one ormore secondary fillers such as glass micro bubbles, mica, perlite, talc,limestone, pyrophyllite, silica, and diatomaceous earth. The fillergenerally comprises from about 25% to about 95% of the weight of thejoint compound based on the total wet weight of the formulation (i.e.,including water). More preferably, the filler comprises from about 55%to about 75% of the total wet weight, and most preferably, from about60% to about 70%.

When the joint compound to be made is a drying type formulation, theamount of filler varies from about 50% to about 98%. The preferredfiller is calcium carbonate in amounts of from about 65% to about 93% byweight of the dry mix for a drying type. Gypsum, or calcium sulfatedihydrate, is also useful as filler in drying type joint compounds.Calcined gypsum, or calcium sulfate hemihydrate, a preferred filler forsetting type formulas, is used in any suitable amount. Preferably, thecalcined gypsum is present in an amount ranging from about 50% to about93% by weight of the dry composition, more preferably, from about 55% toabout 75% by weight of the dry composition. A setting type jointcompound could be based on either an alpha or beta type calcium sulfatehemihydrate. In addition to the calcined gypsum, calcium carbonate maybe used in amounts of from about 0% to about 30% by weight of the drymix for a setting type joint compound.

Additional fillers are also used to impart specific properties to thejoint compounds. Mica, talc, diatomaceous earth, clays, such asattapulgite, sepiolite and kaolin, calcium sulfate dihydrate, calciumsulfate anhydrite, and pyrophyllite are also suitable. Mica aids inreduced cracking of the joint compound as it dries, and is preferred inamounts of up to 25%. It is also preferred to add clay in amounts of upto about 10% to improve the body and workability of the joint compound,and as a rheology modifier. Carbonates are preferably added to settingtype joint compounds, as well as being the preferred filler in a dryingtype joint compound as a bulking agent. The ratio of all fillers to allbinders is preferably in the range of from about 15:1 to about 5:1.

Perlite or expanded perlite is a lightweight filler that may be usedwhere the weight of the compound is important. Use of expanded perlitein a lightweight joint compound is taught in U.S. Pat. No. 4,454,267,which is herein incorporated by reference. Expanded perlite is a verylightweight material that contains many cracks and fissures. It shouldbe treated according to the teachings of U.S. Pat. No. 4,525,388, whichis hereby incorporated by reference, so that the material does notincrease in weight due to water absorbed by capillary action. Thetreated, expanded perlite, when used, is preferably present inconcentrations of at least 5% based on the weight of all ingredients ofthe joint compound, excluding water.

The joint compound of the present invention optionally includes resinmicrospheres as one of the fillers to be used in place of or in additionto expanded perlite in lightweight formulations. Preferred shell resinssuitable for use in the present invention are homopolymers, copolymers,or blends of homopolymers and/or copolymers formed one or more ofacrylonitrile (“ACN”), vinylidene chloride (“VDC”), or methylmethacrylate (“MMA”) monomers. Particularly preferred resins arepolyacrylonitrile (“PACN”), polyvinylidene chloride (“PVDC”), copolymersformed from ACN and VDC, and copolymers found from ACN, VDC, and MMA.The microspheres demonstrate high resiliency to compression withoutcollapse (non-friable) and are able to withstand the exerted shearstress (shear-stability) of a typical joint treatment manufacturingprocess and subsequent customer preparation.

The preferred density of the microspheres is about 0.56 lb/ft³ (0.009g/cc) to about 8.1 lb/ft³ (0.13 g/cc). Microspheres in this densityrange have an optimal effect on increasing the overall volume of thejoint compound. However, they are still heavy enough to allowmeasurement and addition of the microspheres by weight. A lightweightjoint compound utilizing resin microspheres and a method of making itare disclosed in U.S. Ser. No. 09/724,736, which is herein incorporatedby reference.

The joint compound can also include one or more secondary fillers suchas glass micro bubbles, mica, perlite, talc, limestone, pyrophyllite,silica, and diatomaceous earth. The filler generally comprises fromabout 25% to about 95% of the weight of the joint compound based on thetotal wet weight of the formulation (i.e. including water). Morepreferably, the filler comprises from about 55% to about 75% of thetotal wet weight, and most preferably, from about 60% to about 70%.

In some embodiments, fillers can be used in the joint compound. Forexample, calcium carbonate, calcium sulfate hemihydrate, or calciumsulfate dehydrate can all be used as fillers, though other materials canbe used as well. Further, thickeners, preservatives, binders, and otheradditives can be incorporated into the joint compound.

Binders

Any binder that is suitable for use in a joint compound is appropriatefor use in the present invention. The binder is used to enhance theadhesion of the joint compound to its substrate, typically drywall.Acceptable binders include, but are not limited to latex emulsions orspray dried powders; including polyvinyl acetates, polyvinyl acrylicsand ethylene vinyl acetate latexes; and dispersible powders such aspolyvinyl acetates, polyvinyl alcohols, polyvinyl acrylics, ethylenevinyl acetates, vinyl chlorides, styrene acrylics and starches, orcombinations (blends and/or copolymers) thereof.

Preferred binders are soft and pliable rather than being extremely hard.Hard binders are likely to create more fine dust particles compared topliable polymers. Latex binders are most preferred in the presentinvention. The concentration of the latex binder in a conventionalweight joint compound of the invention (14 lbs./gal. density) rangesfrom about 1% to about 2.5% of the total dry weight. The concentrationof binder in a lightweight joint compound ranges from 2% to about 6% ofthe dry weight. In the present invention, the concentration of the latexbinder ranges preferably from about 1% to about 3.5%. As a result of thedust reduction additive comprising CPWB microstructures, a reduction inbinder usage up to almost 100% is possible. Thus by including the DRA,the binder use can be reduced by the following percentage dry weight ofthe joint compound:

1, 5, 10, 14, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80,85, 90, 95, 100.

The weight of the binder can be reduced by a percentage number within arange described by any two numbers above.

Another ingredient usually present in joint compounds is a binder orresin. Suitable binders include polyvinyl acetate, polyvinyl alcohol,ethylene vinyl acetate co-polymer, vinylacrylic co-polymer,styrenebutadiene, polyacrylamide, other acrylic polymers, other latexemulsions, natural and synthetic starch, and casein. These binders canbe used alone or in combination with one another. The amount of bindercan range from about 1% to about 45% of the joint compound total wetweight. More preferably, the binder comprises from about 1% to about 20%of the total wet weight, and most preferably, from about 4% to about14%. More preferably, the binder comprises from about 1% to about 20% ofthe total wet weight, and most preferably, from about 4% to about 14%.Preferred binders are Rhoplex HG 74M and Rhoplex AC 417M acryliccopolymers available from Rohm and Haas, Philadelphia, Pa.

In some embodiments, binders can be used in a joint compound to, forexample, improve bonding to the substrate such as wallboard

Thickeners

Starch may be added to the joint compound in amounts up to about 5% byweight of the dry ingredients to provide good adhesion and increasesurface hardness. Starch also can function as a water retention aid,thickener and internal binder. Preferred starches are usuallypregelatinized for lump-free incorporation into the joint compound.

Bonding between the joint compound and the substrate is improved by theaddition of thickeners, plasticizers and/or polyvinyl alcohol powder.Thickening agents also are added to the joint compound of the presentinvention for other reasons. After water is added to the composition,the thickener becomes hydrated and swells, thereby thickening thecomposition. Thickeners are useful, for example, in helping to createthe body and flow properties commonly associated with joint compounds.Desirably, the thickener is selected so that it substantially hydratesduring the mixing process after water is added to the composition, withlittle or no hydration of the thickener occurring after mixing iscompleted, to prevent formation of lumps in the joint compound.

Suitable thickening agents include hydroxypropyl methylcellulose,hydroxyethyl cellulose, cellulose-based gums, such as xanthan, arabic,alginate, pectin and guar gums, either alone or in combination.Cellulosic thickeners are preferred, with BERMOCOLL® providing the bestresults. Many conventional cellulosic thickeners, such as ethylhydroxyethylcellulose, hydroxypropyl methylcellulose, methyl hydoxypropylcellulose and hydroxyethyl cellulose, are also suitable in the jointcompounds of this invention. The concentration of cellulosic thickenerranges from about 0.05% to about 2% of the dry weight of the jointcompound ingredients. Preferably, it is present in an amount of fromabout 0.1% to about 1.0%.

Many joint compound formulations also contain a cellulosic thickener,usually a cellulosic ether. Suitable thickeners include methylcellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose,hydroxyethyl cellulose, hydroxyethyl methyl cellulose, hydroxyethylhydroxypropyl cellulose, ethylhydroxyethyl cellulose, and sodiumcarboxymethyl cellulose (CMC). These thickeners can be used alone or incombination with one another. The amount of cellulosic thickener canrange from about 0.1% to about 2% by weight of the joint compound. Apreferred thickener is hydroxypropyl methyl cellulose available from DowChemical Company under the trade designation Methocel®.

In some embodiments, clay can be used in a joint compound as, forexample, a non-leveling agent and/or a thickening agent that can controlthe viscosity or rheology of the final product. Clay can also helpenhance or create the water-holding properties of the joint compound.

In some embodiments, thickeners can be used to control the viscosity,affect the rheology, and affect the water holding characteristics of ajoint compound. For example, cellulose ether can be used as a thickener.

Other Additives

Set control additives or chelating agents are also added to setting typeformulations to control set initiation or rate during the shelf life anduse of the product. Preferred set control additives include, but are notlimited to potassium sulfate, calcium sulfate, aluminum sulfate, boricacid, sodium citrate, citric acid, tartrates, or proteinaceousmaterials, or the like, and combinations thereof. Those skilled in theart will recognize that the choice of set control additive and theconcentration depends on the desired hydration time and hydration rate.

When the setting type, ready mix joint compound is to be applied, acatalyst is used to overcome the suspended set state and initiate thehydration reactions. Preferably, a zinc salt catalyst is used, as taughtin U.S. Pat. No. 5,746,822, which is herein incorporated by reference.If a setting type, ready-mix joint compound is utilized without thecatalyst, it functions as a drying type joint compound.

The use of a trimetaphosphate ion is also contemplated for use with thisinvention. Setting type joint compounds utilizing trimetaphosphate ionshave enhanced green strength, final strength or both. However, since thetrimetaphosphate ion is unstable at high pH, it is preferable tomaintain the pH below 9 in compositions where trimetaphosphate ions areused. Use of trimetaphosphate salts in joint compounds is disclosed inU.S. Ser. No. 09/718,279, filed Nov. 22, 2000, herein incorporated byreference.

Other preferred additives of the present joint compound includesurfactants, wetting agents, soaps and alkyl benzene sulfonates. A soap,or detergent, is a complex mixture of ingredients including, but notlimited to acids, bases, antimicrobial agents, antiredeposition agents,colorants, fragrances, defoamers, foaming agents, hydrotropes,moisturizers, preservatives, solvents, thickeners or surfactants,selected from many possible functional groups. Alkyl benzene sulfonateis a specific surfactant that is particularly useful in formulations ofthis nature, as taught in co-pending U.S. application Ser. No.09/724,674, filed Nov. 29, 2000, for a Joint Compound Additive forReduction of Cracking, Cratering and Shrinkage, which is hereinincorporated by reference. The preferred joint compound of thisinvention utilizes sodium dodecyl benzene sulfonate to improve severalproperties of the joint compound including, crater resistance, crackresistance, and shrinkage reduction. In lightweight joint compounds,soaps and alkyl benzene sulfonates also help to decrease the density ofthe joint compound.

A surfactant can also be included in the joint compound formulation. Thesurfactant generally comprises less than about 3.5% of the jointcompound total wet weight, and preferably less than about 0.25%.

Joint compounds provided by the invention are usually made by firstcombining all dry ingredients in a powder mixer. Water and anyadditional wet ingredients are then combined with the dry mixture,either at the point of manufacture or at the time of use. Since themicro-crystalline wax is in a dry powder form, it is preferably meteredinto the other dry ingredients and added to the compound at the powdermixer. Water is then added to the dry ingredients, either duringmanufacture or immediately prior to use, in an amount to obtain thedesired viscosity, usually 300-550 Brabender Units (pin probe). Water ispresent in the slurry in an amount ranging from about 14% to about 75%by weight of the wet composition, more preferably, in an amount rangingfrom about 23% to about 55% by weight of the composition. The inventionis useful in either a ready-mixed form or as a dry powder to which wateris added at the time of use. Either form is suitable for either a dryingtype or a setting type joint compound.

The joint compound described above is useful in finishing of joints fornew construction as well as patching cracks or holes in existing walls.When joints between abutting edges of wallboard are being finished, thearea to be finished is coated with the joint compound. A reinforcingtape is embedded in the joint compound while it is still wet. When dry,a second coating of joint compound is applied to the seam. When dry, theseam is sanded lightly. An optional third coat can be applied, with theseam drying and being sanded in between. Patching of small holes orimperfections in the wall are repaired by applying one or more coats ofjoint compound, allowing the coat to dry and lightly sanding betweencoats. Whether finishing or patching, the final coat is allowed to dryand sanded to create a smooth, monolithic surface over the entire wall.

Another ingredient that can be included in the joint compound of theinvention is a non-leveling agent. Suitable non-leveling agents includeclays such as attapulgus clay, bentonite, illite, kaolin and sepiolite,and clays mixed with starches. Thickeners, such as those describedabove, can also function as non-leveling agents.

To provide a lighter weight joint compound, glass bubbles or a speciallytreated expanded perlite can be added as described in U.S. Pat. No.4,454,267. Additional ingredients which can be utilized in the jointcompound are preservatives, fungicides, anti-freeze wetting agents,defoamers, flocculants, such as polyacrylamide resin, and plasticizers,such as dipropylene glycol dibenzoate.

In some embodiments, perlite can be used in a joint compound to, forexample, control the density, shrinkage, and crack resistance of thejoint compound. In some embodiments, perlite need not be used (e.g.,where weight is not as much of a factor).

In some embodiments, mica can be used in a compound as well. Mica, whichis a low bulk density mineral, may be used as a filler or extender, andmay also improve crack resistance of the joint compound.

In some embodiments of the joint compound gypsum (calcium sulfatedihydrate) can also be used. Gypsum can be used to replace calciumcarbonate, or can be used in conjunction with calcium carbonate. In someembodiments, talc can be included in a joint compound to, for example,enhance application properties and can also be used as a white extenderpigment.

In some embodiments, clay can be used in a joint compound as, forexample, a non-leveling agent and/or a thickening agent that can controlthe viscosity or rheology of the final product. Clay can also helpenhance or create the water-holding properties of the joint compound.

In some embodiments, thickeners can be used to control the viscosity,affect the rheology, and affect the water holding characteristics of ajoint compound. For example, cellulose ether can be used as a thickener.

In some embodiments, binders can be used in a joint compound to, forexample, improve bonding to the substrate such as wallboard.

In some embodiments, a glycol can be used in a joint compound to providefunctional properties to the joint compound such as wet edge, open time,controlling drying time, and freeze/thaw stability.

In some embodiments, other rheology modifiers can also be used inconjunction with, or instead of, some of the above describedcompositions.

In some embodiments, fillers can be used in the joint compound. Forexample, calcium carbonate, calcium sulfate hemihydrate, or calciumsulfate dehydrate can all be used as fillers, though other materials canbe used as well. Further, thickeners, preservatives, binders, and otheradditives can be incorporated into the joint compound.

Other additives can also be added to the described joint compound inaddition to the DRA. In some embodiments, metal siliconate salts suchas, for example, potassium siliconate, as well as silicone basedcompounds such as, for example, poly hydrogen methyl siloxane andpolydimethyl siloxane, could provide advantageous water resistance to ajoint compound. In some embodiments, fluorinated compounds andstearate-based salts could also be used to provide advantageous waterresistance.

Powders from wax emulsions can be particularly advantageous for use in ajoint compound as compared to, for example, non-emulsified and/ornon-stabilized waxes such as melted PEG M750. These non-emulsified waxescan impart severe deleterious effects on the adhesion properties of ajoint compound. Therefore, if the non-emulsified wax is to be used atall, it must be added in very low levels. On the other hand, waxemulsions, such as those described herein, can advantageously increasethe adhesion properties of a joint compound, at least due to theadhesive effects of the stabilizer, and thus can be added at higherdosage levels. The wax emulsion powder can then be useful as they canprovide both low dust properties as well as water repellency to thejoint compound. The wax emulsion can soften or melt when friction isapplied, such as during cutting or sanding. Accordingly, dust can beagglomerated by the softened wax emulsion powder, where it can besecurely held.

Embodiments of the joint compound can be applied in thin layers to asurface. The joint compound can be applied by, for example, using atrowel or other straight edged tool. However, the application andthickness of the layers of joint compounds is not limiting. Further,multiple layers may be applied in order to obtain a smooth, attractivefinished wall. The number or layers applied is not limiting. In someembodiments, each layer can be allowed to dry prior to application ofthe next layer. In some embodiments, a second layer can be applied whenthe first layer is only partially dried. In some embodiments, the jointcompound can be spread over mesh or tape used to connect wallboards. Insome embodiments, the joint compound may also be used to patch andtexture interior walls. In some embodiments, the joint compound can bemade of water, preservative, calcium carbonate, mica, clay, thickener,binder (e.g., latex binder), and a wax emulsion. In addition to a latexbinder, other water soluble binders, such as polyvinyl alcohol, can beused as well.

Other materials, such as talc, binders, fillers, thickening agents,preservatives, limestone, perlite, urea, defoaming agents, gypsum latex,glycol, and humectants can be incorporated into the joint compound aswell or can substitute for certain ingredients (e.g., talc can be usedin place of, or in addition to mica; gypsum can be used in place of, orin addition to calcium carbonate, etc.). In some embodiments, thecalcium carbonate can be replaced either wholly or partially with asurface micro-roughened filler that can further enhance the jointcompound's hydrophobicity. In some embodiments, Calcimatt™, manufacturedby Omya AG, can be used. In some embodiments, cristobalite (silicondioxide) such as Sibelite® M3000, manufactured by Quarzwerke, can beused. These fillers can be used alone or in combination.

In some embodiments, the joint compound can be mixed in water. Thismixture can then be applied to a surface, e.g., hole or joint, and canbe allowed to dry. Once the water evaporates from the mixture, a dry,relatively hard cementitious material can remain. In some embodiments,shrinkage may occur upon drying.

FIG. 3 shows an example of a wall system incorporating an embodiment ofa low-dust joint compound. As shown, the wall system can be made of aplurality of boards 202. There is no limit to the amount of boards orthe positioning of boards next to one another. Where two boards 202 areadjacent to one another, a gap, or joint, can be formed. While theboards 202 themselves may be water-resistant, the joints may allow formoisture to pass through. Therefore, embodiments of the low-dust andwater-resistant joint compound 204 can be spread across the joints. Thecompound 204 can be spread on the joint to completely cover the joint.In some embodiments, the boards 202 can also contain holes. These holescan be formed by nailing the boards 202 into studs, or other attachmentmeans. Regardless of the reason for the hole, the compound 206 can alsobe used to cover the holes. The compound 206 can insert partial throughthe holes, or can cover the top of the holes, or both. The compound 206can cover any fastener, e.g. a screw or nail that is located in thehole. In some embodiments, compound 206 and 204 are the same compound.The application and thickness of the compound 204/206 on the boards 202is not limiting, and common methods of application can be used.

An example formula range of an embodiment of a low-dust water-resistantjoint compound using the above disclosed wax is shown in the below Table4:

TABLE 4 Exemplary Composition of a Low-Dust Joint Compound ComponentRange Water  20-55% Preservatives 0.02-1.0%  Calcium Carbonate  10-50%Mica 0.5-10% Attapulgite Clay 0.2-10% Talc 0.0-10% Perlite 0.0-40%Polyethylene oxide 0.0-10% Polyether siloxane 0.0-10%Micro-crystalline-wax 0.1-20% emulsion powder Latex binder 0.5-10%Cellulose ether thickener 0.1-8.0% 

Further, an example of a specific formulation for alow-dust/water-resistant joint compound can is shown in the below Table5, although other weight percentages may be used:

TABLE 5 Exemplary Composition of a Low-Dust Joint Compound Compound Wt.% Preservative 0.01 Wetting Agent 0.05 Latex Binder 5.89 Water 34.60Microcrystalline-wax 7.36 emulsion powder Cellulose ether 0.55Attapulgite clay 1.84 Mica 7.36 Calcium Carbonate 33.86 Expanded Perlite8.47

Another embodiment of a low-dust/water-resistant/enhanced adhesionready-mix joint compound formula is shown in the below Table 6. In thisembodiment, an optional potassium siliconate additive is incorporated

TABLE 6 Exemplary Composition of a Low-Dust Joint Compound Raw MaterialWt. % Preservative 0.20% Latex (CPS 716) 6.50% Water 36.70% EmulsifiedPowder Comprising 3.80% CPWB Microstructures Potassium Siliconate(Silres BS 0.20% 16) Cellulose Ether 0.60% Clay (Attagel 30) 1.90% Mica6.10% Limestone (MW 100) 35.20% SilCel 43-34 8.80%

Low-Dust Joint Compounds—Comparative Examples

To assess the reduction of dust formation during the sanding process bysamples created with joint compound compositions of the presentinvention, the samples are compared with three other commerciallyavailable products. Testing is performed on all products upon thoroughmixing. The commercially available products compared herein are:

-   -   (1) LaFarge North America, Inc.'s (“LaFarge”) from United States        Gypsum Company's (“USG”);    -   (2) Sheetrock Lightweight All Purpose Plus 3 with Dust Control        from USG; and    -   (3) ProForm DustTech from National Gypsum Company (“NSG”).

Test Procedure

A test chamber is constructed as described at Col. 6, Lines 26-56 inU.S. Pat. No. 6,358,309, which is incorporated by reference herein. Apower sander made by Makita Corporation, model BO4556 is used to sandthe specimens. The peak or highest level of dust particles measured foreach sample is recorded. (See U.S. Pat. App. Pub. No. 20110065839).

The test procedure for measuring the quantity of airborne particlesgenerated when sanding the hardened joint compound is as follows. First,each test specimen is prepared according to a specific formulation. Thetest specimens are approximately five inches long; one and one-halfinches wide; and one quarter of an inch thick (5″×1½″×¼″). Beforesanding, each test specimen is allowed to completely harden for at least24 hours at room temperature in an environment where the relativehumidity generally ranges from about 25% to about 75%.

FIG. 4 shows the Test Enclosure 2 for sanding the three test specimensand measuring the quantity of generated airborne dust particles. TheEnclosure 2 is a rectangular box 6 feet high, 4 feet wide, and 2 feetwide (6×4′×2′). The top (6), the bottom (8), the side (10), and the rearwalls (12) of the Enclosure 2 are constructed of wood, and the frontwall (14) is constructed of transparent Plexiglas®. A generallytriangular access opening (16) located about one foot above the bottomwall (8) is provided in the front wall (14) to allow the individualconducting the test to insert her hand and arm into the enclosure andsand the specimen. The access opening (16) has a base dimension of about7½ inches and a height of about 8½ inches. A movable cover member (18)is provided to allow the Enclosure 2 to be completely sealed whensanding is completed. To sand the three specimens, the cover (18) isarranged in its UP position as shown by the solid lines in FIG. 4. Whensanding is completed, the cover (18) is pivoted downwardly to completelycover the access opening (16) as shown by phantom lines (18′).

As shown, three specimens of joint compound are prepared on a section ofwallboard (20) and the section of wallboard (20) is clamped to amounting block (22) arranged within the Enclosure 2. When tested, thespecimens are located about twelve inches above the bottom wall (8) ofthe enclosure. Each specimen is tested individually and after each test,the enclosure is cleaned so that the quantity of airborne dust particlesmeasured less than 0.5 mg/m3. A particle counter (24) for measuring thequantity of airborne particles was mounted in the right side wall aboutforty-eight inches above the center of the three specimens.

The power palm sander included a 4½-inch×4.375-inch pad equipped with a120-grit mesh sanding screen mounted over a 5-inch×3½-inch×¾-inch open,semi-rigid, non-woven, heavy-duty, stripping, backing pad available fromMinnesota Mining and Manufacturing Company, St. Paul Minn. Sanding isperformed at a sanding speed of approximately 14,000 OPM (orbits perminute) using ordinary sanding pressure. Ordinary sanding pressure isdefined as the amount of pressure typically required to sand a hardenedjoint compound. Sanding pressure, therefore, is the manual pressuretypically applied by an ordinary person when sanding a joint compound.

It will be recognized that the sanding pressure can vary depending onthe hardness of the joint compound. Sanding is continued until thespecimen is completely sanded. That is, the entire thickness of thespecimen is sanded so that a generally smooth wall surface is produced.Care is taken to ensure that sanding is discontinued before the drywallitself is sanded. The time required to sand each specimen variesdepending on the hardness of the joint compound and the sandingpressure. The quantity of airborne dust particles is measured from thetime sanding is initiated until several minutes after sanding isdiscontinued. In general, the level of airborne dust is measured untilthe level decreased to less than 50% of its peak level. The quantity ofairborne dust is measured using a DUSTTRAK™ aerosol monitor model 8520available from TSI Incorporated, St. Paul, Minn. The particle countermeasures the number of particles having a size of less than or equal to10 microns. In the Examples, the peak or highest level of airborne dustmeasured during the test is presented. The test procedure for measuringthe quantity of airborne particles generated when sanding the hardenedjoint compound is largely the same as described in U.S. Pat. No.6,358,309, which is incorporated herein by reference. In essence, a testspecimen as prepared using each of the commercial products andformulations described above.

The CPWB microstructure emulsion formulation from which a powder isprepared is comprised of a wax, for example, micro-crystalline wax, anemulsifier, usually a carboxylic acid or ester that can be saponifiedvia a reaction with a base, and a stabilizer polyvinyl alcohol. Suitableemulsifiers are montan wax, rice wax, carnauba wax, and any such waxthat is composed of a mixture of acids and esters. Standalone acids fromC5 to C100, such as stearic acid, can also be used in place of theaforementioned natural waxes. Likewise, standalone esters of similarcarbon atom chain length can also be used.

Suitable bases include any compound that is capable of saponifying theester carboxylate group, or deprotonating the carboxylic acid proton.Suitable bases are inorganic basis such as potassium hydroxide andammonium hydroxide. Likewise, suitable organic basis are monoethanolamine, diethanol amine, ad triethanol amine.

Powders from two emulsions are prepared for comparison with thecommercially available low-dust joint compounds. The first emulsioncomprises a paraffin wax based core. The second emulsion comprises amicrocrystalline-wax based core with the CPWB microstructure.

In one embodiment, when powder from microcrystalline-wax-basedmicrostructure based emulsion is used as a dust reduction additive tothe joint compound, the joint compound improves its dust reductioncapability, over and above the simultaneous improvement in adhesion,over the paraffin-wax based emulsion.

The joint compound's ability to reduce dust is measured as peak airbornedust production in mg/m³ units, and for the joint compound comprisingthe microcrystalline-wax-based microstructure emulsion powder, the peakairborne dust (PAD) number is reduced by the following percentagenumbers, depending upon the content of the emulsion powder in the jointcompound 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 75, 80, 85%, 90%and 95%, and 98%.

In some embodiments of the present invention the PAD number is reducedby a percentage residing in between a range defined by any two numbersabove, including the endpoints of such range.

The wax emulsion is made by heating the emulsifier and the paraffin-waxin a vessel such that both become molten. In a separate vessel, ameasured quantity of polyvinyl alcohol is mixed with water at roomtemperature after which the mixture is heated to about 180° F. Themolten paraffin/montan mixture is then combined with the hotwater/polyvinyl alcohol mixture which, upon passing through a charlottemill, emerges as a stable wax emulsion where the polyvinyl alcohol istethered to the paraffin surface, largely encapsulating the paraffin. Arepresentative formula of the wax emulsion is shown in Table 7.

TABLE 7 Representative Formula of CPWB Microstructure Based InventiveWax Emulsion Ingredient Content % Water 60.3 Polyvinyl alcohol 3 Wax33.5 Montan wax 3 Monoethanol amine 0.2 Total Wt. 100 % Polyvinylalcohol 3.0% % Paraffin 33.5%

Commercial Low-Dust Joint Compounds

TABLE 8 Airborne Dust Generated by Commercial Low-Dust Joint CompoundsCommercial Low Dust Average Peak Airborne Joint Compound Dust (mg/m³)LaFarge Rapid Coat 130 Sheetrock Dust Control 67 ProForm DustTech 74

The emulsion described above is reduced to powder as discussedpreviously. In Table 9, the percentage of powder of the CPWBmicrostructure DRA emulsion will be different from what is listed inthat, the listed percentages are that of the emulsion if the emulsionwas added, as is, and not powderized. Stated another way, for example,the 3.1% percent addition would be with the moisture in the emulsion,but once it is reduced to the powder form, the percent addition would bedifferent—a lower percentage.

Joint Compound with CPWB Microstructure-Based DRA Emulsion Powder

Five wax emulsion powders including one Control emulsion powder areprepared. The Control emulsion powder has 0% inventive powder comprisingCPWB microstructures. Experiment 1 has 2%; Experiment 2 has 3.1%;Experiment 3 has 4.7%; and Experiment 4 has 6.2% wax emulsion powderincluded in the joint compound.

The Control sample generates approximately 104 mg/m³ of peak airbornedust. With the addition of CPWB microstructure based inventivecomposition of the present invention, it is speculated that the peakairborne dust (PAD) production is reduced from 104 mg/m³ to about 20mg/m3, for the 6% concentration of the powder prepared from CPWBemulsion as percentage of the joint compound weight. It is speculatedthat a mere 2% powder prepared from CPWB emulsion will be able to reducethe PAD production from 104 mg/m³ to about 50 mg/m³, which is asignificant improvement in PAD generation. The commercial low dustcompound LaFarge has a peak dust production number of 130 mg/m³. Thus,at a 6% inclusion of powder prepared from CPWB emulsion, the peakairborne dust production will reduced by 85%. Similarly, the commerciallow dust compounds Sheetrock Dust has a peak dust production 67 mg/m³and ProForm DustTech has a PAD production of 74 mg/m³. Thus, at 6%inclusion of powder prepared from CPWB emulsion the PAD production isreduced by about 47% and 73%.

The comparative improvement in the PAD numbers at variety of powderprepared from CPWB emulsion is provided in Table 9.1 below.

TABLE 9.1 PAD value Improvement in of the Inventive Composition overCommercial Products Inventive Joint Inventive Joint Inventive JointInventive Joint Inventive Joint Compound-- Compound-- Compound--Compound-- Compound-- Comparative Powder prepared from Powder preparedfrom Powder prepared from Powder prepared from Powder prepared fromCommercial CPWB emulsion CPWB emulsion CPWB emulsion CPWB emulsion CPWBemulsion Low Dust Compound content 0% content 2% content 3.1% content4.7% content 6.2% LaFarge Rapid Coat  20% 61% 74% 82% 85% (130 mg/m³)Sheetrock Dust Control −36% 25% 49% 66% 70% (67 mg/m³) ProForm DustTech−40% 32% 54% 69% 73% (74 mg/m³)

Thus, the CPWB microstructure based DRA emulsion based joint compoundshowed a significant and surprising peak airborne dust reductioncompared to the control as well as the commercially available compounds.

From the foregoing description, it will be appreciated that inventivedevices and approaches for low-dust/and wax emulsions have beendisclosed. While several components, techniques and aspects have beendescribed with a certain degree of particularity, it is manifest thatmany changes can be made in the specific designs, constructions andmethodology herein above described without departing from the spirit andscope of this disclosure.

Certain features that are described in this disclosure in the context ofseparate implementations can also be implemented in combination as wellas in a single implementation. Conversely, various features that aredescribed in the context of a single implementation can also beimplemented in multiple implementations separately or in any suitablesub-combination. Moreover, although features may be described above asacting in certain combinations, one or more features from a claimedcombination can, in some cases, be excised from the combination, and thecombination may be claimed as any sub-combination or variation of anysub-combination.

Moreover, while methods may be depicted in the drawings or described inthe specification in a particular order, such methods need not beperformed in the particular order shown or in sequential order, and thatall methods need not be performed, to achieve desirable results. Othermethods that are not depicted or described can be incorporated in theexample methods and processes. For example, one or more additionalmethods can be performed before, after, simultaneously, or between anyof the described methods. Further, the methods may be rearranged orreordered in other implementations. Also, the separation of varioussystem components in the implementations described above should not beunderstood as requiring such separation in all implementations, and itshould be understood that the described components and systems cangenerally be integrated together in a single product or packaged intomultiple products. Additionally, other implementations are within thescope of this disclosure.

Conditional language, such as “can,” “could,” “might,” or “may,” unlessspecifically stated otherwise, or otherwise understood within thecontext as used, is generally intended to convey that certainembodiments include or do not include certain features, elements, and/orsteps. Thus, such conditional language is not generally intended toimply that features, elements, and/or steps are in any way required forone or more embodiments.

Conjunctive language such as the phrase “at least one of X, Y, and Z,”unless specifically stated otherwise, is otherwise understood with thecontext as used in general to convey that an item, term, etc. may beeither X, Y, or Z. Thus, such conjunctive language is not generallyintended to imply that certain embodiments require the presence of atleast one of X, at least one of Y, and at least one of Z.

Language of degree used herein, such as the terms “approximately,”“about,” “generally,” and “substantially” as used herein represent avalue, amount, or characteristic close to the stated value, amount, orcharacteristic that still performs a desired function or achieves adesired result. For example, the terms “approximately”, “about”,“generally,” and “substantially” may refer to an amount that is withinless than or equal to 10% of, within less than or equal to 5% of, withinless than or equal to 1% of, within less than or equal to 0.1% of, andwithin less than or equal to 0.01% of the stated amount.

Some embodiments have been described in connection with the accompanyingdrawings. The figures are drawn to scale, but such scale should not belimiting, since dimensions and proportions other than what are shown arecontemplated and are within the scope of the disclosed inventions.Distances, angles, etc. are merely illustrative and do not necessarilybear an exact relationship to actual dimensions and layout of thedevices illustrated. Components can be added, removed, and/orrearranged. Further, the disclosure herein of any particular feature,aspect, method, property, characteristic, quality, attribute, element,or the like in connection with various embodiments can be used in allother embodiments set forth herein. Additionally, it will be recognizedthat any methods described herein may be practiced using any devicesuitable for performing the recited steps.

While a number of embodiments and variations thereof have been describedin detail, other modifications and methods of using for the same will beapparent to those of skill in the art. Accordingly, it should beunderstood that various applications, modifications, materials, andsubstitutions can be made of equivalents without departing from theunique and inventive disclosure herein or the scope of the claims.

What is claimed:
 1. A method of using joint compound composition thathas low-dust property and optionally improved adhesive property and/orimproved water resistance property, said method comprising: (I) applyingsaid composition to a joint between adjacent wallboard panels; (II)allowing said composition to dry; and (III) sanding said driedcomposition. wherein said joint compound composition comprises a dustreduction additive emulsified powder made from an emulsion comprisingcolloidally-protected-wax-based (CPWB) microstructures.
 2. The method asrecited in claim 1, wherein said dust reduction additive emulsifiedpowder is made from an emulsion comprising said CPWB microstructurecomprising: (A) a wax core, wherein said wax core comprises amicro-crystalline wax component and/or a non-micro-crystalline waxcomponent, wherein said micro-crystalline wax component comprises atleast one linear alkane wax defined by the general formula CnH2n+2,where n ranges from 13-80, wherein said non-micro-crystalline waxcomponent comprises at least one wax selected from the group consistingof animal-based wax, plant-based wax, mineral wax, synthetic wax, a waxcontaining organic acids and/or esters, anhydrides, an emulsifiercontaining a mixture of organic acids and/or esters, and combinationsthereof; and (B) a polymeric shell, wherein said polymeric shellcomprises at least one polymer selected from polyvinyl alcohol,polyvinyl alcohol copolymers, polyvinyl alcohol terpolymers, polyvinylacetate, polyvinyl acetate copolymers, polyvinyl acetate terpolymers,cellulose ethers, polyethylene oxide, polyethyleneimines,polyvinylpyrrolidone, polyvinylpyrrolidone copolymers, polyethyleneglycol, polyacrylamides and poly (N-isopropylamides), pullulan, sodiumalginate, gelatin, starches, and combinations thereof.
 3. The method asrecited in claim 2, wherein said polymeric shell comprises polyvinylalcohol.
 4. The method as recited in claim 1, wherein saiddust-reduction additive emulsified powder is made from an emulsion thatfurther comprises a base; and a dispersant.
 5. The method as recited inclaim 1, wherein the weight of said dust reduction additive emulsifiedpowder is in the range of from about 0.1% to about 20% by weight of saidjoint compound composition.
 6. The method as recited in claim 1, whereinthe quantity of dust generated upon sanding of said low-dust jointcompound composition is reduced at least by 5%.
 7. The method as recitedin claim 1, wherein the quantity of dust generated upon sanding of saidlow-dust joint compound composition is reduced at least by 80%.
 8. Amethod for reducing the quantity of dust generated by a joint-compoundcomposition, said method comprising the steps of: (I) providing ajoint-compound composition comprising a filler, a first water, binder,and at least one of a defoamer, wetting agent, preservative, fungicide,thickener, non-leveling agent, surfactant, and a solvent; and (II)subsequently adding a sufficient quantity of a dust-reduction additiveemulsified powder as described in claim 1 to said joint-compoundcomposition to reduce the quantity of dust generated by sanding thehardened joint-compound composition by at least 5%.
 9. The method forreducing the quantity of dust generated by a joint-compound as recitedin claim 8, wherein the quantity of dust generated by sanding saidhardened drywall joint-compound is reduced by at least 80%.
 10. Themethod of claim 7, wherein said joint compound composition has a contactangle of about 60° to about 150°; and/or wherein said joint compoundcomposition has a Cobb value of about 5.0 to about 100 g/m2.
 11. Amethod for reducing the quantity of dust generated by a joint-compoundcomposition, said method comprising the steps of: (I) providing ajoint-compound composition comprising a filler, a first water, binder,and at least one of a defoamer, wetting agent, preservative, fungicide,thickener, non-leveling agent, surfactant, and a solvent; and (II)subsequently adding a sufficient quantity of a dust-reduction additiveas described in claim 2 to said joint-compound composition to reduce thequantity of dust generated by sanding the hardened joint-compoundcomposition by at least 5%.
 12. The method for reducing the quantity ofdust generated by a joint-compound as recited in claim 11, wherein thequantity of dust generated by sanding said hardened drywalljoint-compound is reduced by at least 80%.
 13. The method of claim 11,wherein said joint compound composition has a contact angle of about 60°to about 150°; and/or wherein said joint compound composition has a Cobbvalue of about 5.0 to about 100 g/m2.
 14. A low-dust joint compoundcomposition comprising a dust reduction additive emulsified powder asdescribed in claim
 2. 15. The low-dust joint compound composition asrecited in claim 14, further comprising at least one component from afiller; a binder; a thickener; a non-leveling agent; a preservative; arheology modifier; and a surfactant.
 16. The low-dust joint compoundcomposition as recited in claim 14, wherein: said filler is selectedfrom calcium carbonate (CaCO3), calcium sulfate dihydrate (CaSO4 2H2O),calcium sulfate hemihydrate (CaSO4-1/2H2O), glass micro bubbles, mica,perlite, talc, limestone, pyrophyllite, silica, diatomaceous earth,cristobalite, a micro-roughened filler, clay, and combinations thereof;said binder is selected from polyvinyl acetate, polyvinyl alcohol,ethylene vinyl acetate co-polymer, vinylacrylic copolymer,styrenebutadiene, polyacrylamide, acrylic polymers, latex, naturalstarch, synthetic starch, casein, and combinations thereof; saidthickener is selected from methyl cellulose, hydroxypropyl cellulose,hydroxypropyl methyl cellulose, hydroxyethyl cellulose, hydroxyethylmethyl cellulose, hydroxyethyl hydroxypropyl cellulose,ethylhydroxyethyl cellulose, sodium carboxymethyl cellulose, andcombinations thereof; and said non-leveling agent is selected fromattapulgite clay, bentonite, illite, kaolin, sepiolite, clays mixed withstarches, and combinations thereof.
 17. The low-dust joint compoundcomposition as recited in claim 14, wherein the weight of said dustreduction additive is in the range of from about 0.1% to about 20% byweight of said low-dust joint compound composition.
 18. The low-dustjoint compound composition as recited in claim 16, wherein the weight ofsaid dust reduction additive is in the range of from about 0.1% to about10% by weight of said low-dust joint compound composition.
 19. Thelow-dust joint compound composition as recited in claim 14, wherein thepeak air-borne dust generation of said low-dust joint compound is lessthan 100 mg/m3.
 20. The low-dust joint compound composition as recitedin claim 14, wherein the quantity of dust generated upon sanding of saidlow-dust joint compound composition is reduced at least by 5%.
 21. Thelow-dust joint compound composition as recited in claim 14, wherein thequantity of dust generated upon sanding of said low-dust joint compoundcomposition is reduced at least by 80%.
 22. The low-dust joint compoundcomposition as recited in claim 14, further comprising at least onecomponent from a silicone, a siliconate, a fluorinated compound, astearate, or a combination thereof.
 23. The low-dust joint compound ofclaim 21, wherein the silicones, siliconates, fluorinated compounds, orstearates are selected from the group consisting of metal siliconatesalts, potassium siliconate, poly hydrogen methyl siloxane, polydimethylsiloxane, stearate-based salts, and combinations thereof.